"The Mystery Duelist, Part 1", known as "Challenge from the Past - The Terrifying Zera" in the Japanese version, is the fiftieth episode of the Yu-Gi-Oh! anime. It is the season 2 premiere, as well as the first episode in the Battle City arc. It first aired in Japan on April 10, 2001, and in the United States on November 16, 2002.
It's the morning of the school soccer game, Téa arrives at the Game Shop to meet and walk to school with Yugi, she greets Yugi's Grandpa who calls upstairs to his grandson whose getting ready for school alerting him that Téa has arrived. Whilst preparing his things for school, Yugi exchanges his former brown rope for a chain in order to keep his Millennium Puzzle as safe as possible, as thus far it has been proven that nearly everyone is trying to get their hands on it, most recently Pegasus and Yami Bakura. In conversation, with Yami, the latter says that the chain is vital since the Millennium Puzzle connects two, he also states that he senses that fate has more in store for them though he is unaware of what specifically lies ahead for the two heroes. Yugi vows to his spirit friend that the two are in it together no matter what. Yugi then goes downstairs and outside to greet Téa and the two bid his grandfather goodbye and rush off to walk to school, already late and close to missing the game.
Whilst walking to school, Téa and Yugi come across a hidden hooded figure who identifies himself as a fortune teller, who offers to reveal Yugi's future to him. Interested to know the fete of himself and the pharaoh, Yugi approaches the stranger, Téa alerts Yugi to hurry up as she doesn't want to miss the soccer game. As Yugi approaches, the stranger notices the Millennium Puzzle around the latter's neck and claims that he can only reveal one's future by holding a personal item and suggests Yugi's Millennium Puzzle which he identifies as a "necklace" as a cover up his awareness of the Millennium Items. Though first hesitant, Yugi reluctantly hands over his Millennium Puzzle showing that he's desperate to discover what lies ahead for him and his spirit friend, even though Téa warned him that handing his Millennium Puzzle over to a stranger may be a bad idea, which is later proven to be true when the mysterious unidentified man steals the item and runs off with it as soon as Yugi's hands it over. Yugi runs after the thief, while Téa takes the over direction to attempt to cut the latter off around the other side. Yugi looses track of the thief but comes across an alleyway with arrows signifying a direction for one to follow. Yugi realises that the thief clearly wants Yugi to follow him, although it is obvious that he is being led into a trap, Yugi follows regardless with no choice in the matter as it is the only way to get back his puzzle and avoid losing the spirit of the latter in the process.
Téa has made it to the other side but there is no sign of the thief of Yugi's Millennium Puzzle or Yugi himself, she runs into Bakura who is still under control of the evil spirit of the Millennium Ring, after Tristan's failed attempt to free him from that control by throwing the ring away back at Duelist Kingdom. Téa tells Bakura about the situation, Bakura encourages Téa to keep searching whilst claiming that he will go and find help. After Téa runs back off thanking Bakura, the evil spirit of the ring takes control, presumably angry with someone else for stealing the Millennium Puzzle which he desires along with all seven of the Millennium Items, two of which he owns already - his own item, the Millennium Ring and Pegasus' Millennium Eye which he stole from the latter back at Duelist Kingdom -, he then proceeds with his mission of finding and stealing the Millennium Puzzle, and heads off to find Yugi and the thief, using the power of his Millennium Ring to compass his way. He later finds himself in the alleyway of arrows which he switches round whilst proceeding through to confuse Téa, Tristan and Joey, who he knows will eventually come looking for Yugi, thus preventing them from finding their friend and interfering with Yami Bakura's plans.
Yugi, meanwhile, still confused on why the thief wants him to follow him, has made it to the last arrow which leads him into a shack where he reencounters the thief and duelling arena inside. The thief explains that in order to win back the puzzle Yugi will have to duel him and the winner will keep the item. The thief explains that merely stealing the puzzle won't grant him the power he desires and to gain the rightful control over the item's power he must win it from him in a duel (hence leading Yugi to the duel arena at the shack). Yugi refuses to duel at first, saying that he shouldn't have to duel for his puzzle as it is his, but is reluctant to accept the challenge as its the only way to win back his puzzle which is currently in the possession of a thief, chained to Yugi's duel table. Yugi is forced to duel alone, as the puzzle is not within Yugi's reach, thus weakening his bond with Yami Yugi and preventing them from connecting with each other (in the Japanese version, the thief staged the Duel so Yami Yugi would take over to protect Yugi, giving the thief victory over the pharaoh as well as possession of the Puzzle. However, Yami Yugi senses the trap and holds back). For once Yugi is duelling at high states alone, without the spirit to guide him and his friends to cheer him on.
The duel begins, Yugi takes the first turn with Celtic Guardian in Attack Mode, while his thief sets a monster, which Yugi then attacks, and in doing plays into his opponent's hands, activating the flip effect of his face down, Cyber Jar destroying Yugi's Celtic Guardian and itself and forcing each play to draw five cards and summon any Level 4 monsters they draw, Yugi only draws one which he plays face down in defence position; meaning his opponent had cleverly tricked him and in turn forcing him to discard and waste four cards, due to exceeding the hand size limit. When the thief plays two machine monsters Mechanicalchaser and Ground Attacker Bugroth, Yugi realises the identify of the player he is up against; the only player he knows with a deck of machine monsters, Bandit Keith. Yugi addresses the latter by his name, who then removes his hood revealing himself and confirming the truth of Yugi's predictions. Yugi is confused on why Bandit Keith would track him down to steal his puzzle, as he recalls the last time he saw Keith, at the Duelist Kingdom final, during the latter's duel with Joey which he lost and in turn got ejected from the island by Pegasus on account of cheating. The former then speaks confirming not to be Bandit Keith and in fact someone else who is possessing and controlling Keith and speaking through him by means of another Millennium item. The stranger then explains that following Keith's ejection from the island, he and his followers traveling via boat at sea rescued the latter from drowning and took control over him. The duel continues as Keith builds up a strong attack force with Machine King which gains 100 attack points for every machine monster on the field, including itself. Keith maintains his advantage in the duel destroying Yugi's defenses with Machine King and building up his attack force to increase the mechanical menace's attack points even more.
Meanwhile, Téa has headed to school to chase up Tristan and Joey, the three friends head off to search for and help Yugi. Whilst on the way out they are confronted by the soccer coach, who questions them on their reasons for checking out early when volunteering to help with soccer game. Tristan lies saying Téa's cat is sick and needs to be taken to the vet; Téa in response fakes crying begging the coach to let them go, hinting that her fictional cat may be dying. Convinced and touched, coach lets them go.
Back at the duel, Yugi fights back with Gaia the Dragon Champion destroying Mechanicalchaser and decreasing both Keith's life points and Machine King's attack points. Keith counters on his next turn with Machine Conversion Factory powering up Machine King making it stronger than Yugi's Dragon Champion and allowing it to destroy the latter. After drawing Summoned Skull, Yugi realises how to overcome Keith's machine monsters and activates Makiu, the Magical Mist to rust Keith's machines and destroy Machine King with Summoned Skull's electricity means of attack. Meanwhile, Yugi's friends have traced up Yugi's steps in the alleyway where they find the arrows all mixed up, confusing them on which way to go.
Despite being under control, Keith is still using the same cheating tactics he used during his duel with Joey back at Duelist Kingdom - hiding rare cards under his sleeves and sneaking them into his hand, which he does after activating Graceful Charity, allowing him to draw three cards from his deck and discard two in exchange, in which he illegally sneaked three cards (two of which were two rare cards; Zera Ritual and Zera the Mant) from under his sleeve on the top of his deck before drawing through the effect of Graceful Charity (hinting that the stranger was probably aware of Keith's classic cheating method and decided to use it to his advantage against his opponents). Keith then summons his greatest monster Zera the Mant through the Zera Ritual magic card and puts an end to Yugi's Summoned Skull.
Yami Bakura has finally chased up Yugi and the thief of the Millennium Puzzle, arriving outside the shack of where the duel is taking place. While Yugi's friends, Téa, Joey and Tristan are lost and confused by the mixed up arrow signs and unaware of where to go.
Featured Duel: Yugi Muto vs. "Bandit" Keith Howard
Turn 3: Yugi
Yugi draws. "Celtic Guardian" attacks and destroys Keith's Set monster, "Cyber Jar" (900/900). The Flip effect of "Cyber Jar" activates, destroying every monster on the field. After that happens, the Flip Effect of "Cyber Jar" lets both Yugi and Keith excavate the top five cards from their respective decks and Special Summon any Level 4 or lower monsters them drew in Attack Position or face-down Defense Position before adding the remaining cards to their respective hand. Yugi Sets a monster while Keith Special Summons "Mechanicalchaser" (1850/800) and "Ground Attacker Bugroth" (1500/1000) in Attack Position. On Yugi's End Phase, he discards four cards due to exceeding the hand size limit.
Turn 4: Keith
Keith draws. He then Normal Summons "Machine King" (2200/2000) in Attack Position. Due to the effect of "Maching King", it gains 100 ATK for each Machine-Type monster on the field. There are currently three ("Machine King": 2200 → 2500/2000). "Machine King" attacks and destroys Yugi's Set monster, "Silver Fang" (1200/800). On Keith's End Phase, he discards two cards due to exceeding the hand size limit.
Turn 6: Keith
Keith draws "Megasonic Eye" and subsequently Normal Summons it (1500/1800) in Attack Position ("Machine King": 2500 → 2600/2000). "Machine King" attacks and destroys Yugi's Set monster, "Giant Soldier of Stone" (1300/2000).
Turn 7: Yugi
Yugi draws "Curse of Dragon" and subsequently Normal Summons it (2000/1500) in Attack Position. Yugi then Normal Summons "Gaia The Fierce Knight" (2300/2100) in Attack Position. He then activates "Polymerization" to fuse "Curse of Dragon" with "Gaia The Fierce Knight" and Fusion Summon "Gaia the Dragon Champion" (2600/2100) in Attack Position. "Gaia the Dragon Champion" attacks and destroys "Mechanicalchaser" (Keith 2000 → 1250) ("Machine King": 2600 → 2500/2000).
Turn 8: Keith
Keith draws. He then switches "Megasonic Eye" and "Ground Attacker Bugroth" to Defense Position. Keith then activates "Machine Conversion Factory" to increase the ATK and DEF of every Machine-Type monster he controls by 300 ("Machine King": 2500 → 2800/2000 → 2300; "Ground Attacker Bugroth": 1500 → 1800/1000 → 1300; "Megasonic Eye": 1500 → 1800/1800 → 2100). "Machine King" attacks and destroys "Gaia the Dragon Champion" (Yugi 2000 → 1800).
Turn 9: Yugi
Yugi draws "Summoned Skull". He then activates "Makiu, the Magical Mist" to decrease the ATK and DEF every Machine-Type monster by 300 ("Machine King": 2800 → 2500/2300 → 2000; "Ground Attacker Bugroth": 1800 → 1500/1300 → 1000; "Megasonic Eye": 1800 → 1500/2100 → 1800). He then Normal Summons "Summoned Skull" (2500/1200) in Attack Position. "Summoned Skull" then gains 750 ATK due to the effect of "Makiu, the Magical Mist" ("Summoned Skull": 2500 → 3250/1200). "Summoned Skull" attacks and destroys "Machine King" (Keith 1250 → 500). On Yugi's End Phase, the effect of "Makiu" expires ("Summoned Skull": 3250 → 2500/1200).
Turn 10: Keith
Keith draws "Graceful Charity" and subsequently activates it to draw three cards and discard two cards (he illegally placed three cards on top of his Deck right before drawing through the effect of "Graceful Charity"). Keith then activates "Zera Ritual" to Tribute "Ground Attacker Bugroth" and "Megasonic Eye" in order to Ritual Summon "Zera the Mant" (2800/2300) in Attack Position. "Zera the Mant" attacks and destroys "Summoned Skull" (Yugi Muto 1800 → 1500).
- Yugi switches out the rope necklace on the puzzle for a stronger chain, fearing for its safety.
- Bandit Keith never appeared again in the regular manga; this episode was used to help with plot holes that the Dungeon Dice Monsters episodes left behind, as it didn’t follow the manga exactly.
Differences in adaptations
- Cut from the beginning of the episode are scenes of Yugi's mother.
- All the writing on Domino City is erased from the dub.
- The words "TO BE CONTINUED" are added at the end of the dub episode.
- The gun is removed from the flashback.
- When re-aired in the 2010s, this season was titled Rulers of the Duel
- In the dub, Marik tries to force Yugi to hand over the Millennium Puzzle, in the original japanese version, Marik tries to force Yugi to reveal Yami Yugi's presence.
- After "Cyber Jar" is played face-down, it is seen face-up from behind Keith.
- In the dub, Keith refers to "Cyber Jar" as a Machine monster, when in fact it's a Rock monster.
- In the Japanese, Megasonic Eye is shown as a Level 4 monster when it's actually Level 5.
The following cards appeared in this episode. Cards in italics debuted here.