Halldor

Harald is the leader of Team Ragnarok competing in the WRGP. He is the owner of "Odin, Father of the Aesir". He resembles Jack Atlas.

Pre-Team Ragnarok
Harald received his Rune Eye while acting as a military pilot. During a flight, he and another comrade were threatened by the mysterious appearance of clouds. While on the storm, unable to see anything, Harald's Rune Eye appeared and with its power allowed him to see through the storm and prevent crashing on mountains.

Long after this event, Harald begin researching about the Norse mythology involving Ragnarok and found "Odin, Father of the Aesir" in a treeroot.

Harald then began searching for others who might also have a Rune Eye, with the help of his servant Sebastian. This leading him to finding Dragan's father who gave him "Thor, Lord of the Aesir", with the condition of delivering that card to its son. After meeting Dragan who had survived an avalanche because of the Rune Eye protecting him, Harald convinced him to use "Thor".

Lastly Harald along with Brave traveled to an island where "Loki, Lord of the Aesir's" card was. Upon finding it, Brave steals it and tries to escape on a boat. As Dragan, Harald and Sebastian follow after him, Brave's boat crashed against a boulder and sends him flying towards a pillar of rock and almost crashes.

However the final Rune Eye appeared on his eye and a mysterious thunderbolt destroyed the pillar. After the three of them catch up with Brave, he says that the card is his, though Harald acknowledges saying that "Loki" has chosen him.

World Riding Grand Prix
Harald, along with his companions were on a plane where they were flying towards New Domino City for the WRGP finals. At the time the Three Emperors of Yliaster achieved Falsification of history. Harald along with the others noticed that the Aesir had protected them from the wave.

Later Harald and his team appeared publicly to host an exhibition duel against the other teams in the WRGP, where Dragan chose to duel Jack Atlas. During the duel, after Dragan Summons "Thor, Lord of the Aesir" and attacks "Red Dragon Archfiend", the two monsters emit a strange wave of energy while battling. Because the force began to destroy the building, the duel was called off.

Before their match against Team Five D's, his comrades witness how the Spiral building is emerging into their world. Yusei Fudo, Jack and Crow Hogan arrive, and Harald realizes that the Mark of the Dragon allows them to see the building as well. He reveals that they know Team New World is the one behind the upcoming crisis.

Harald then proceeds to tell them the story behind the Rune Eye, as well as that of the 3 Polar Gods. After this Yusei asks him to cooperate with them in stopping Yliaster. However Harald reveals that the three Polar Gods don't want to because of Yusei's father been the one who caused Zero Reverse and began all this. And that because of this Yusei himself also carries a destiny of destruction.

Therefore Harald declares that the semifinals will decide who fights against Yliaster. When Harald finally faces against Yusei in the semifinals, Harald pushes him into a corner as he has all 3 Polar Gods on the field. Still Yusei, with the power of the Crimson Dragon and "Shooting Star Dragon", was able to defeat him and with this Team Ragnarok loses and Team 5D's proceeds to the finals. After the duel ends and both duelists get back to the pits, Harald recognizes Yusei's strategy of countering the "Eye of Odin" to win the duel. He then uses its Rune Eye and notices that behind Yusei and "Shooting Star Dragon" is the Crimson Dragon. Harald takes this as evidence that the Polar Gods now acknowledge Yusei and his friends as comrades.

After Dragan, Brave and Sebastian arrive to where he is, Sebastian questions him if they should leave the fate of the world on their hands. Harald then responds that Yusei's fate won't bring destruction but instead a road to brighter future.

When the Three Emperors of Yliaster appear to the Signers the day previous to the WRGP finals, Harald and its teammates are also present. This as they explain to Team 5D's that the fate of the world lies in them winning the match as that would cause the Ark Cradle to disappear

Harald and his team watch as Team 5D's defeat New World and later congratulate them on their victory. They also witness the appearance of Ark Cradle.

Harald, Dragan and Brave appear again on their Duel Runners. Brave states that theirs were working because they were using the power of their Rune Eyes. Harald further explains that they weren't affected by the negative rotation, implying that the Duel Runners of Team 5D's should work because of the power of the Crimson Dragon.

Later on, the team speaks with Yusei alone, stating that they will create a path to the Ark Cradle. Harald tells Yusei of the legend of the Rainbow Bridge Bifrost, a path that connects the human world with the the divine world. He explains that he and his teammates will use the energy of the Ener-D Reactor to create and manifest a path on the Daedalus Bridge.

They travel with Yusei and Bruno to the reactor. Connecting their runners to it, Harald, Dragan and Brave summon the Aesir to increase Ener-D's volume and reverse its rotation. Harald then calls forth Bifrost, creating a path from the Daedalus to the Ark Cradle.

As Yusei and his friends travel on the path, Team Ragnarok struggle to maintain the bridge. Eventually, their runners reach their limits and explode, causing the Aesir and Bifrost to disappear. Their fate is currently unknown.

Deck
Harald plays a Nordic Ascendant Deck, focused on the Summoning of "Odin, Father of the Aesir" and supporting the Aesir monsters of his teammates, which revive at each End Phase if destroyed.