Leo Akaba, also commonly known as the Professor, is a character in the Yu-Gi-Oh! ARC-V anime, the father of Ray, and then later husband of Henrietta and father of Declan, though he abandoned his second family before the adoption of Riley. Originally a resident of the Original Dimension, he is responsible for masterminding the Duel Academy's attacks on the Xyz Dimension to complete the Arc Project and Revival Zero both of which were designed to restore his home and bring back his daughter. Due to his position and machinations, he functions as the primary antagonist of the series until the revival of the Supreme King Z-ARC.
Leo Akaba is a middle-aged tan-skinned bald man with light blue eyes. He wears a purple colored militaristic outfit with several black buttons which resembles the outfit of Vellian Crowler, a purple cape with a black ending, and a pair of gray boots. He also has a black belt with a red line which both end in a button on the front, and what appear to be red circular strings across his chest with a pair of black gloves on his hands. His perhaps most noticeable traits are the armored plate at the left side of his head with what appears to be a red circular lens, and pronounced blood vessels on the top of his head. The red lens can be used for scanning information.
In his youth, Leo had a full head of dark gray hair, and wore a light blue flannel shirt with gray slack pants. When he performed experiments on Duel Monsters, he wore a lab coat. All of the members of the Akaba family have a slight card suit motif; Leo's is the spade, shown by the spade-shaped collar of his coat, and his "Spirit" Deck.
Before traveling to the Fusion Dimension Leo was inventive and benevolent, expressing a desire to use the ARC System to innovate Dueling and considering Yusho to be a friend. After regaining his memories, he seems to be heartless enough to abandon his home and family, seen when he forcefully sent Declan back to Paradise City, and his lack of empathy for the people that his soldiers seal into cards; indeed, Leo actually believes this to be justified. He is pragmatic; he does not punish his subordinates for their failures in contrast to his former subordinate Jean-Michel Roget. This extends to actions that he feels that he is required to take; while he earlier voiced the opinion that the people of the Standard Dimension are not enemies of Duel Academy, he was willing to oppose them in order to recover Celina from the dimension.
He appears to have charisma and excellent leadership skills, as apparently everybody at Duel Academy obeys him and finds it extremely difficult to betray him (though not without exception). The only times he has authorized force has been with Yuri, Dennis, and Barrett's missions to capture Celina and her dimensional counterparts. Unlike many people in Duel Academy, Leo takes no joy in the pain nor suffering inflicted by his subordinates. He was shown to be visibly disturbed when the Doktor used Parasite Monsters to brainwash his daughter's dimensional counterparts and reacted in horror when Yuri ruthlessly sealed Alexis Rhodes into a card.
During his confrontation with Yusho, Declan, and Riley, Leo showed that he is a very serious man, and feels guilt after the damage he inadvertently caused by unleashing Zarc and his daughter's sacrifice that sundered the Original Dimension to stop him. Nonetheless despite his remorse, his fixation with reviving his daughter causes him to believe his attacks on the other dimensions are justified regardless of the suffering and maltreatment he caused to innocent people. Following Zarc's defeat, Leo appears to have adopted a more reflective mindset, showing remorse for the actions he took in his quest to revive Ray, his disregard of Ray's reincarnations as their own individuals, and ruining the lives of their loved ones by kidnapping them. In the English Dub, Leo also reveals that while he knew that Ray's incarnations all have their own loved ones in the current life, and that his daughter sacrifice had brought salvation for everyone, the pain of losing his daughter was so great that he couldn't bear to live without her, motivating his entire quest of bringing her back. 
"零" ("rei") means "zero" or "nothing", while "王" ("ō") means "king". The normal reading of Leo's name would be "Reiō"; however, it is read as "Reo" instead, so Reo's name is pronounced exactly like "Leo" in Japanese.
His dub name comes from his Japanese name: Leo/Lion is mostly known as "king of beasts". In addition, his name can be separated into "Le' 0" which means "the zero", both linking to his Japanese name.
Leo was a resident of the Original Dimension and a professor developing new possibilities with the ARC System. He then decided to use Duel Monsters with it and found out the compatibility between them were perfect. After studying the monsters, Leo was able to give them mass and was praised all over the world for leading Dueling into a new era. However, a Duelist named Zarc started Dueling in a violent manner and eventually declared his desire to destroy the entire world. Leo could only watch in horror as Zarc attacked everyone with his four dragons and Leo escaped the stadium with his daughter. He heard her say that the monsters were angry with Leo, and remembered that Duel Monster cards were said to have souls. At that moment Leo realized that by giving monsters actual physical bodies with mass he inadvertently awakened their souls thus they became self-aware. He watched Zarc fuse with his four dragons to become Supreme King Z-ARC and was shocked that they had become one.
While Supreme King Z-ARC destroyed the city, Leo created four cards with natural energy to seal him away. He prepared to battle Zarc, but Ray took the cards from Leo to prevent him from sacrificing himself. Leo pursued her, and he watched from behind a barrier as Ray used the cards to split her and Supreme King Z-ARC.
Leo found himself in a strange town where there wasn't any Fusion, Synchro, or Xyz Summonings, only "standard" Duels. He tried to touch a monster, but his hand went right through it and the Duelist controlling the monster explained to Leo that it was Solid Vision. With no memory of his former life, Leo began to recreate the ARC System due to the knowledge left in his brain's subconscious. Leo met with Yusho Sakaki and he showed him the ARC System by giving a "Thunder Kid" mass, claiming to Yusho that it would take Dueling beyond fantasy. The two joined forces and they successfully developed the ARC System for public use, leading to the creation of Action Dueling. At some point, he gave Yusho "Binding Swords of Impact", but he was unaware that Yusho couldn't use it in Duels due to a bug where it caused the ARC System to go offline and remained materialized.
At some point Leo married a woman named Henrietta and the two had a son named Declan. He became the founder of Leo Corporation and Leo Institute of Dueling which introduced the concept of Action Duels in addition to reintroducing Fusion, Synchro, and Xyz Summoning to the Standard Dimension. During that time, he scanned his distant memories as he slowly recalled the events of his previous life. As his memories returned bit by bit, Leo began to obsess with the thought of Ray's survival, and that she may still be alive somewhere in the Four Dimensions. One day, he abandoned the company and left for the Fusion Dimension without telling anyone in his family to search for her.
Leo met a girl named Celina at Duel Academy who resembled Ray. He decided to scan Celina's memories for any traces of Ray’s memories due to their resemblance and the bracelet that Celina wore, but was disappointed as she has no past memories of being Ray. However, Leo remembered that Ray's shadow had split into four along with Zarc and the world, concluding that his daughter had been divided and sent to each of the Four Dimensions as different versions of herself. Leo took control of Duel Academy, taking the title "Professor", and he used it as a frontline base to enact the plan to reunite the Four Dimensions back into one, with the Revival Zero initiative being key in restoring his daughter in the process. One day, he and Celina met Yuri, a boy who resembled Zarc, and they told Yuri of his crucial role in the Arc Project. He took the boy under his wing and became his parental figure, teaching everything to Yuri. However, Leo appeared to mostly let Yuri have his own way, never disciplining him properly, causing the boy to have loose morality and result in birth of the "second Zarc" who only dueled for a challenge and pleasure, never cared about people's suffering. 
Eventually, his son Declan stumbled into Duel Academy through a teleportation device intending to confront Leo about abandoning his family, but Leo and the Obelisk Force caught him trying to aid Celina escaping. Celina, who was attempting to escape with Declan's aid, complained to Leo about being stuck at Duel Academy while her comrades were preparing to attack the Xyz Dimension, but he refused to add her to the vanguard squad. Declan also protested that Leo had abandoned Leo Corporation, to which Leo asked him if he had crossed dimensions just to find him, confusing Declan even further. The Obelisk Force troops apprehended Celina, and Leo told her that he would definitely find her and bring her back to Duel Academy, regardless of where she ran. He then used a wristwatch-like device to send Declan back to the Standard Dimension, but not before telling him about the Fusion Dimension and he planned to use Duel Academy to help him bring the worlds together.
Arc League Championship
When Declan and Shay were watching the Duel between Yuto, Sora Perse, and Yuya Sakaki, Yuto revealed that Duel Academy invaded the Xyz Dimension. Declan stated that this was due to Leo Akaba's ambitions. After Sora was transported back to Duel Academy within the Fusion Dimension, Leo watched over his ARC-V machine as it absorbed the life energy of the cards that contained the people of Heartland. His aide informed him that the forced return program of Sora Perse's Duel Disk had activated once Sora revealed his mission to their enemies within the Standard Dimension. However, Leo clarified that the Standard Dimension was not their enemy and that investigating Sora's memories would explain the situation. After doing so, he informed Yuri about Zuzu Boyle's existence, claiming that she was the fourth piece that he was looking for. Because of this, he ordered Yuri to bring Zuzu to Duel Academy.
When Sora asked Leo directly to let him return to Standard, Leo granted his request, under the conditions that Obelisk Force would accompany him and that he would retrieve Celina and bring her back to Duel Academy.
Friendship Cup Finals
After hearing Dennis' report that Zuzu and Celina were in the Synchro Dimension's New Domino City, Leo gave Barrett a new mission to go to the Synchro Dimension with the Obelisk Force and capture Zuzu and Celina. He also informed him that Yuri would also come to the Synchro Dimension.
After Mamoru sent a report about Pendulum Summoning being used in the Xyz Dimension, Leo sent Gloria and Grace Tyler to Heartland City to help defeat the Lancers. As a precaution he also sent the Obelisk Force as backup in case the Tyler sisters lost. After Leo received Celina's report that she had captured Zuzu, he mused that it was time for Yusho Sakaki to learn the truth, while he watched Yusho arrive at Duel Academy with The Doktor.
As Doktor monitored how his "Parasite Fusioner" had made Rin follow his orders, Leo recognized his results but warned him that Rin and her counterparts are important to the Arc Project and not to be harmed. He looked over at another monitor to see Yusho and Alexis Rhodes. When Sanders contacted him about the Lancers landing on the island's north side, Leo told him to carry out the mission according to the plan and take Yuya Sakaki down. Leo watched Shay Obsidian and Kite Tenjo argue over Lulu's sanity while listening to the Doktor wonder if the Obsidian siblings' bond could beat the Professor's will, and merely watched as the Doktor ran to do more improvements after Shay defeated Lulu. He watched the Duel between Alexis and Yuri, but was horrified at Yuri's wish to seal everyone in all dimensions into cards to prove that he was the strongest, evening standing up when Yuri sealed Alexis into a card. Leo watched Yuya Duel Lulu in the Doktor's lab, and he noticed something when Yuya told Lulu he was Yuto. He rose up in surprise when Yuya turned into Yuto (though he could not see the transformation himself) and he wondered if the second personality in Yuya was something else. After the Doktor informed Leo that he had captured Yuya, Leo had his students admit Declan, Riley, and Yusho to see him, and he told Yusho that he had been waiting for him.
Leo was unfamiliar with Riley, and he wondered who she was. Yusho passionately asked Leo to stop his plans, claiming that a genius like Leo should know better than to cause suffering to innocent lies. Leo refuted Yusho's praise, and he claimed that he wasn't a genius as he revealed to Yusho that the ARC System was just reproduced from existing technology that had been developed in the United World. Leo asked Yusho and Declan why the only difference between the Four Dimensions were the Summoning methods, and he revealed both his history there and that of Zarc and Zarc's attacks against humanity before Zarc fused with his four dragons to become Supreme King Z-ARC. Leo explained that he had felt responsible for creating Zarc and that couldn't afford to give up, even if it meant sacrificing himself to save his world. When Declan called Leo's story a myth to calm Riley, Leo angrily told him that he had witnessed the end of the world because of Supreme King Z-ARC.
Yusho questioned Leo about Zarc, and Leo explained that the four dragons were responsible for combining into that monster and when it split, the world did as well for each summoning method. To Leo's surprise, one of his staff contacted him and informed him that Yuya Sakaki had escaped from the Doktor's lab. Leo ordered the Doktor to bring the girls as fast as he could as Yuya entered his inner chambers. Yusho tried to convince him not to involve the children and tell him the full story, and Leo mused that Yuya had finally gotten this far. He told Yusho that Yuya wasn't his son. Yuya told Leo to give Zuzu back, and Leo claimed that he was trying to bring back the truth. Zuzu and her counterparts appeared behind him in tubes and the Doktor explained that they were. The Doktor voiced his desire to deal with Yuya, but Leo was skeptical of the Doktor's chances. The Doktor expressed confidence in his work and protested that as fellow researchers he and Leo should share a similar curiosity in confronting challenging research. Leo agreed, and he turned the Doktor into a card, comparing the Doktor's dangerous thinking with his own past curiosity that had caused the birth of Supreme King Z-ARC, which freed the girls from the control of the Doktor's Parasite Monsters.
Yuya tried to run to Zuzu, but Leo blocked his path and he revealed how his daughter Ray had defeated Zarc and caused the world to split. He revealed that he had eventually regained his memories in the Standard Dimension and departed to search for Ray in the Fusion Dimension, where he had found Celina. Leo explained that he had deduced that Ray had divided into fragments in each of the Four Dimensions and he explained that the Bracelet girls were reincarnations of Ray and that he planned to revive her, using the Arc Project for that purpose. Leo revealed ARC-V, which would bring back the fifth dimension and Ray, completing Revival Zero. He asked Declan to lend him his power to defeat Yuya, as like the Four Dimensions and the Bracelet girls, Zarc had split into four as well, thus making Yuya a reincarnation of Zarc. He noted that Yuya had already merged with Yuto and increased in power, declaring they had to bury that destructive power to prevent the devil's revival. Declan refused to help him and declared that he would follow his beliefs with Yuya, and Leo warned him that his belief would bring about a ruined world and he challenged them to a Duel.
Leo revealed that he had already started the process to fuse the girls back into Ray and the Four Dimensions back into one. Yuya Pendulum Summoned "Odd-Eyes Pendulum Dragon", which Leo angrily remembered as Zarc's "Odd-Eyes Dragon". He observed Declan Pendulum-Fusion, Synchro, and Xyz Summon, noting that he took up arms while Leo was gone. Declan used "Dark Contract with the Monopoly Seal" to prevent Leo from using the three summoning methods that Declan had used. Leo told Declan that Yuya was an avatar of Zarc and shouldn't deny it any longer by joining him but Declan still refused. Declan retorted that Zarc wouldn't be reviving and the Four Dimensions would be at peace if it weren't for Leo's desire to fuse the dimensions, but Leo still believed that Zarc would revive even if he hadn't created ARC-V, especially since Yuya had already absorbed Yuto. To everyone's shock, Leo revealed his ability to Pendulum Summon, calling out "Spirit Tech Force - Pendulum Governor" and "Spirit Gem - Salamander Core". He then used the effect of "Pendulum Governor" to Tribute "Salamander Core" and destroy "Odd-Eyes" and "D/D/D Flame King Genghis", unsealing his Fusion Summoning. The effect "Pendulum Governor" also prevented Declan from attacking with "D/D/D Gust King Alexander" and "D/D/D Wave King Caesar". Leo criticized Declan's leadership of the Lancers, noting that their one plan didn't the consider the possibly of the enemy exceeding their expectations. The girls' capsules started to glow, and Leo revealed that it was only a matter of time until ARC-V started up, declaring that Ray's revival was at hand. Leo tried to convince Declan to join him again until he noticed Yuya's awakening, which he revealed to be due to Zarc dwelling inside him. He told Declan to make the decisive decision and join him to prevent the devil's revival. Yuya Fusion Summoned "Performapal Gatlinghoul" and used its effects to severely damage Leo, preparing to defeat him by destroying "Pendulum Governor".
Leo used the Pendulum Effect of "Spirit Reactor" to negate the effect by using Declan's monsters. The near-defeat prompted Leo to contact one of his staff for ARC-V's energy reading, and he ordered the input speed of ARC-V to be increased before Zarc could revive. Declan brought out "D/D/D Doom King Armageddon" to circumvent the effect of "Pendulum Governor", but Leo used "Dis-swing Fusion" to stop Declan's attack, take control of "Doom King Armageddon", and Fusion Summon "Master Spirit Tech Force - Pendulum Ruler". He laughed and told Declan he hadn't changed, making him easy to read and a second-rate Duelist. He attempted to destroy "Gatlinghoul", but Yuya used "Twin Big Shields" to protect "Gatlinghoul". Leo vowed to defeat Yuya before Zarc could absorb his Synchro and Fusion alter egos and revive completely. As he used the effects of his "Core" monsters to systematically destroy Yuya and Declan's card, his staff informed him that ARC-V was reaching 30%, pleasing Leo as they closed in on daughter's revival. He ordered them to increase the energy input since ARC-V should able to accept it faster and activate ARC-V as soon as possible. Leo destroyed "Gatlinghoul" and attacked directly with "Doom King Armageddon", giving Declan's monster the honor of destroying Zarc's alter ego, but Yuya used "Evasion" to dodge it. Yuya threatened to bury him, and Leo claimed that it was useless due to "Pendulum Ruler" and "Doom King Armageddon". Yuya brought back Odd-Eyes" and Xyz Summoned "Dark Rebellion Xyz Dragon", and his use of Zarc's monsters caused Leo to declare that Yuya no longer existed. To his surprise, Yuya brought out "Odd-Eyes Raging Dragon" and used its effect to negate and destroy all other cards on the field bar Leo's monsters. Yuya destroyed "Doom King Armageddon", and the effect of "Dis-swing Fusion" caused Declan to take the damage instead. His staff informed Leo that ARC-V was entering the designated range, and he urged them to hurry and revive Ray. "Raging Dragon" destroyed "Pendulum Ruler" and blasted Leo into his throne, but as Yuya prepared to deal the finishing blow, Yusho used "Restraining Sword of Impact" on Yuya, which terminated the Duel. Yusho explained that the card was bugged and didn't disappear when the ARC System went offline. Yusho explained that he had brought the card to remind Leo of the basics and had considered using it to bind him, but never thought he would use it on his own son. He departed to stop Yugo and Yuri's Duel, asking Leo to free the girls.
Leo ignored Yusho's wishes once he learned that ARC-V was at 50% and he left his throne room to watch over ARC-V. As the throne room sealed itself off, Leo declared that they could no longer turn back. He wondered how long Yuya's bindings would last, wanting to revive Ray before they could break. He stated that by putting the girls into ARC-V first, the worlds would become one and Ray would revive along with the cards he had created. Leo ordered his staff to hurry and increase the life energy, and when it reached 60%, he ordered Zuzu to be transferred into ARC-V. Yuri absorbed Yugo, and as he watched Yuri searching for Yuya, Leo ordered his staff to transfer Lulu into ARC-V, so Ray could revive as soon as possible. As he had Rin transferred into ARC-V, he begged Yusho to endure his Duel with Yuri so Ray could revive soon. Yusho was defeated, and Leo watched Yuya and Yuri's Duel. He worried that Zarc would revive if the Duel ended, and he accelerated Celina's transfer into ARC-V before moving his throne away from ARC-V as it activated. His staff informed of ARC-V's startup and the Fusion Dimension's interference, and Leo stated that ARC-V would expand and capture the Four Dimensions to mix into it and revive the Original Dimension and Ray. He activated the Isolation Dome to prevent Zarc's integration into ARC-V until the four cards and Ray could return. To his horror, Ray didn't revive and he ordered a scan for any life reactions inside the core. No life readings could be confirmed, and Leo begged his daughter to revive.
As his throne approached ARC-V, Leo desperately checked to see why Ray wasn't reviving and he wondered if the life energy that he had collected was insufficient, and he screamed Ray's name in anger. Only the Natural Energy Cards had appeared, and Leo added them to his Deck and joined the Duel against Zarc, receiving an intrusion penalty. Leo asked Zarc if he remembered him as Zarc defeated Sylvio Sawatari and Crow Hogan. Leo vowed to defeat Zarc on Ray's behalf and make the Four Dimensions one again, and he sent "Pendulum Ruler" to the Graveyard to fulfill the activation conditions for the Natural Energy Cards. Declan joined the Duel as well, explaining to Leo that he wasn't the only person who had caused Zarc to become evil. Leo prepared to use the four cards, but Zarc activated "Supreme Disdain" to discard them and inflict damage for each sent card, defeating Leo. He was blasted into the building and Declan saved him from falling to his death.
Leo punched the ground in anger, his plan to seal Zarc foiled, but Declan declared that they still had hope as everyone that Dueled Zarc believed Yuya's soul was inside him. Zarc revealed that he was the true founder of Pendulum Summoning, and vowed to win his next battle with Ray, to Leo's surprise. Leo reflected how Ray used the to split Supreme King Z-ARC but at a cost. Zarc began attacking Declan with his Supreme King Dragons, and Leo was confident Declan wouldn't take damage due to the Pendulum effects of his monsters. Unfortunately, Zarc's repeated attacks defeated Declan, but Moon Shadow saved them from the attack of "Supreme King Z-ARC". He was surprised when Ray returned by possessing Riley's body and pleased when she used the Natural Energy Cards to destroy "Z-ARC" and his "Supreme King Dragons". Riley and Ray defeated Zarc, and as the "Supreme King Dragons" emerged from "Supreme King Z-ARC", Leo noted that the world was about to split into four again.
Following the battle with Zarc, Leo returned to his efforts of reviving Ray. He became aware of Yuya's revival in the Standard Dimension, now the "Pendulum Dimension", and managed to collect what appeared to be Ray's spirit, though he was unsure that it was Ray and theorized that as Zarc's fragments had revived as Yuya, Ray's fragments would eventually revive as Zuzu Boyle. Shay Obsidian, Lulu's older brother, Yuya, Sora and Alexis entered his chambers, and Shay demanded to know where Lulu was. Leo claimed that Lulu was gone, just as Yuto was. Shay grabbed Leo's shoulder and tried to punch him, and as Alexis tried to stop Shay, Leo replied that Shay could hit him all he wanted. He expressed remorse for being so caught up in reviving Ray that he had dismissed the lives of the four girls that she had split into. Shay lowered his fist, and he left to Duel Yuya. Leo continued working to revive Ray while everyone watched Yuya's Turbo Duel with Jack Atlas. As he worked on Ray's revival, Leo noticed her waveforms were responding to something and to his surprise, the reaction began to increase in speed. Leo watched in shock as Ray awakened, and Ray sent her father to the Pendulum Dimension to witness her revive, as Leo had theorized, as Zuzu Boyle. Listening to Riley, who contained Zarc's spirit, laugh, Declan mentioned that Zarc was probably laughing as well. Leo agreed and suggested that the worlds had become one again through Yuya's Dueling.
Leo absolutely hated Zarc and refers to him as a "Devil". He blames himself for causing Zarc's rampage and is devoted to ensure he will not revive once the Four Dimensions are merged.
Leo appears to be apathetic to his son as Declan asserted his father would not ransom him if he were kidnapped. Declan is shown to have a deep grudge towards Leo for neglecting him and his mother and created the Lancers to fight against him. He also displayed a hatred for his father's ambition due to the suffering he and his army have caused, and for abandoning his family.
However, after revealing the truth about the Four Dimensions and his plans to revive Ray, Leo asked his son to help him destroy Yuya in order to prevent Zarc's revival, and was infuriated when Declan rejected the offer. Throughout the Duel, Leo repeatedly tried to convince Declan to join his side and criticized his moves when they backfired. Declan on the other hand continued to reject Leo's offers and accused him of being the true "devil" for sacrificing thousands of lives for his plans.
Declan's antagonistic stance against his father seemed to have softened later on, however, as he willingly teamed up with Leo to duel Zarc. Declan also stated that Leo was not solely responsible for Zarc's revival, but that it is the fault of everyone who bore evil in their hearts, which Zarc was able to feed upon to facilitate his emergence. After Leo was defeated by Zarc, Declan caught his father and hauled him up to safety.
Celina is shown to be annoyed the fact that Leo doesn't allow her to go to the front lines and forces her to stay in Duel Academy. Leo is shown to be interested in Celina's unknown ability and Celina is often trying to impress Leo so that he can allow her to join the war with her comrades.
It was later revealed that Leo's confinement of Celina is due to her being one of Ray's reincarnations. As a result, Leo is very protective of Celina to a degree; expressing discomfort at her brainwashing.
Despite his origin, Yuri is shown to be Leo's most trusted student, as it is seen he entrusted him to capture Zuzu and her counterparts knowing how he will handle the situation carefully and is confident in his abilities. In return Yuri is very loyal to him and will carry out his orders without question, albeit he does so to fulfill his malicious pleasure, as seen when Yuri threaten to card Zuzu, but doesn't do so because of Leo's orders. But in reality, he greatly fears Yuri as evidenced by his reaction when he watched Yuri sealing Alexis Rhodes into a card.
Leo appears to trust Sora as much as he trusts Yuri, and when Sora requested to return to the Standard Dimension, Leo allowed him to go and ordered him to return Celina to Duel Academy. Unlike Yuri, Sora ignores his orders in favor of his more personal goals, tracking down Shay instead of Celina, and eventually betrayed him.
According to Yusho they apparently had a fruitful professional relationship due to their collaboration in developing Action Duels and the ARC System.
Leo fears and despises Yuya due to him being one of Zarc's reincarnations. Out of all of Zarc's reincarnations, he feels threatened by Yuya the most as he has already absorbed Yuto. He wants to destroy Yuya at all costs to prevent Zarc's return before continuing with Revival Zero. After the battle with Zarc and the revival of Ray as Zuzu Boyle, Leo demonstrated a more positive outlook, suggesting that Yuya's Dueling had made the dimensions one again rather than his plans.
Leo runs a "Spirit" Deck focused on Pendulum Summoning "Spirit Tech Force - Pendulum Governor" and the "Spirit Gem" monsters. Leo's strategy is oriented towards Tributing the "Spirit Crystal" monsters with the effect of "Pendulum Governor" so he can use the Tributed monster's effects twice during the turn. As the "Spirit Crystal" monsters have effects that destroy cards on the field and damage the player that controlled the destroyed card, this allows Leo to simultaneously remove multiple opposing cards at once and heavily damage the opponent.
To prevent the opponent from destroying "Pendulum Governor", Leo can use its effects to keep the opponent from attacking it, along with the Pendulum Effect of "Spirit Reactor" to keep it from being destroyed by card effects. He is also capable of taking advantage of his opponent's Pendulum Scales by being able to copy them using the Pendulum effect of "Spirit Reactor", enabling him access to Pendulum Summoning. For additional offensive power, Leo can Fusion Summon "Master Spirit Tech Force - Pendulum Ruler", whose monster effects are augmented versions of those found on "Pendulum Governor", which it uses as a Fusion Material. This is done so via the effect of "Dis-swing Fusion", which not only acts as a counter if his opponent manages to get around the attack sealing effects of his Spirit Reactors, but also allows him to Fusion Summon with only one monster on his opponent's turn.
For his Duel against Zarc, Leo added the Natural Energy Cards to his Deck, intending to defeat Zarc in the same manner that Ray did.
In the past, Leo is shown to possess several cards with Lion-motif during his research into the Arc System.
|Declan Akaba & Yuya Sakaki, Yusho Sakaki||128-129||No result|
- ↑ Yu-Gi-Oh! ARC-V episode 40: "Stealth Warriors"
- ↑ 2.0 2.1 Yu-Gi-Oh! ARC-V episode 8: "Bad Business"
- ↑ 3.0 3.1 3.2 3.3 Yu-Gi-Oh! ARC-V episode 41: "Bracing For Battle"
- ↑ 4.0 4.1 Yu-Gi-Oh! ARC-V episode 36: "Sora's Secrets: Part 2"
- ↑ 5.0 5.1 Yu-Gi-Oh! ARC-V episode 99: "A Vicious Cycle"
- ↑ "TV Tokyo Yu-Gi-Oh! ARC-V Characters". May 17, 2015. http://www.tv-tokyo.co.jp/anime/yugioh-arcv/chara/index_6.html.
- ↑ But when she was taken from me, separated into each dimensions, as much joy as it brought everyone, twice as much heartache it brought to me.
- ↑ 8.0 8.1 8.2 Yu-Gi-Oh! ARC-V episode 126: "An Evil Ascends"
- ↑ 9.0 9.1 9.2 9.3 9.4 9.5 9.6 Yu-Gi-Oh! ARC-V episode 127: "Revival Zero"
- ↑ 10.0 10.1 Yu-Gi-Oh! ARC-V episode 129: "A Duel Within"
- ↑ 11.0 11.1 Yu-Gi-Oh! ARC-V episode 123: "123 Fusion Destruction"
- ↑ 12.0 12.1 Yusho: You've caused enough suffering for ten lifetimes. Maybe if Leo.. gave you a couple hours of detention everyday you wouldn't be such a terrible person!
- ↑ Yu-Gi-Oh! ARC-V episode 25: "Battle Between Buddies: Part 1"
- ↑ Yu-Gi-Oh! ARC-V episode 27: "Challengers Assemble"
- ↑ Yu-Gi-Oh! ARC-V episode 37: "A Dark Reflection"
- ↑ Yu-Gi-Oh! ARC-V episode 76: "Plans of Attack"
- ↑ Yu-Gi-Oh! ARC-V episode 106: "An Academic Test"
- ↑ Yu-Gi-Oh! ARC-V episode 108: "Twins with Tudes"
- ↑ Yu-Gi-Oh! ARC-V episode 109: "Surprise Showing"
- ↑ Yu-Gi-Oh! ARC-V episode 116: "A Towering Achievement"
- ↑ Yu-Gi-Oh! ARC-V episode 117: "Grip of the Parasite"
- ↑ Yu-Gi-Oh! ARC-V episode 118: "Survival of the Fittest"
- ↑ Yu-Gi-Oh! ARC-V episode 119: "Family Face Off"
- ↑ Yu-Gi-Oh! ARC-V episode 124: "Paraside Seeing"
- ↑ Yu-Gi-Oh! ARC-V episode 125: "Rise of the Parasites"
- ↑ Yu-Gi-Oh! ARC-V episode 128: "What Lurks Beneath"
- ↑ Yu-Gi-Oh! ARC-V episode 130: "Duel Interrupted"
- ↑ Yu-Gi-Oh! ARC-V episode 131: "Sibling Standoff"
- ↑ Yu-Gi-Oh! ARC-V episode 133: "A Father's Finale"
- ↑ Yu-Gi-Oh! ARC-V episode 134: "Relentless"
- ↑ Yu-Gi-Oh! ARC-V episode 135: "Time to Reunite!"
- ↑ Yu-Gi-Oh! ARC-V episode 136: "A Most Brutal Duel"
- ↑ Yu-Gi-Oh! ARC-V episode 139: "Clash Talk"
- ↑ Yu-Gi-Oh! ARC-V episode 140: "A Ray of Hope"
- ↑ Yu-Gi-Oh! ARC-V episode 145: "Shay's Rage"
- ↑ Yu-Gi-Oh! ARC-V episode 146: "One Way Street to Defeat"
- ↑ Yu-Gi-Oh! ARC-V episode 148: "That's a Wrap!"