Takeruhiko Yamato (倭 健彦, Yamato Takeruhiko) is the King of the Kina Kingdom, one of the countries that form the Seven Seas Alliance. After the Kou Empire Civil War ended, Yamato disappeared along with the whole island due to Aladdin's help. he disappeared with his Metal Vessel, and due to his actions, he is considered as one of the three most wanted criminals in the whole world.
Takeruhiko appears in Japanese-styled armor, wielding a large katana behind him. He has black hair that spikes up and is crowned by a headgear with horns that give him the appearance of a demon. He has a large tattoo on his back depicting an Oni, a type of yōkai in Japanese mythology. This could be in reference to the culture of his country.
Takeruhiko seems to be a bit of a gentleman, as he said that a samurai from the Kina Kingdom cannot strike down girls. However, he also seems to be ambitious and war-loving, as he quickly brushes that attitude and strikes down Koumei despite the long distance between them.
Takeruhiko and Darius Leoxses come to Hakuryuu's aid and stand in the way of Kouha and Kougyoku. He comments how the fight would be a bit of a dilemma seeing as a samurai from his kingdom cannot strike down girls (accidentally mistaking Kouha for a female). Takeruhiko presents himself, and, when questioned by Kouha why the king of the Kina Kingdom is meddling with the Kou Empire's civil war, both Takeruhiko and Darius proclaim that the kings have come to the aid of a sworn friend of the Seven Seas Alliance.
Both Takeruhiko and Darius introduce themselves again, and Kouha is surprised to hear that even the Kina Kingdom is part of the Seven Seas Alliance. When Hakuryuu joins them both, Kougyoku questions this, prepared to attack, but Kouha stops her. He then asks why the Seven Seas Alliance invaded Kou Empire's territory, due to their belief in "not to invade and not to be invaded", but Darius brushes it off, saying they have come to stop the conflict in the territory of their sworn friend. Darius then says that they have come to the side of the true commander of the Kou Empire, Hakuryuu, and explains that the Kou Empire made a vow to the Seven Seas Alliance and became their ally, surprising Kouha and Kougyoku.
Kouha realizes the true meaning of the war, and explains to Kougyoku that it is all a pretext for the Seven Seas Alliance's intervention, and Kougyoku, realizing the Alliance's leaders were watching all along, says that it is cowardice. Takeruhiko says that he honestly did not like how that man handled things, but Darius says that complaints aside, Takeruhiko should carry out the orders given to him without failure. Takeruhiko says he understands, and proclaims that he shall take the head of the enemy general, unsheathing his sword and activating his Djinn Equip. Kouha and Kougyoku quickly assume his target is Kouha, but he ignores them and strikes Koumei, using Caim's ability to quickly reduce the distance between them.
Three years after Sinbad created the International Alliance, Yamato became one of the three "world's most wanted" criminals. He committed the greatest crime of going into hiding along with his Metal Vessel and Djinn. Not only that, Yamato and his island inexplicably disappeared.
He seems to be able to control water, as he rides a large wave towards the battlefield, even when they are in the middle of the plains.
Caim is the Djinn that Takeruhiko obtained when he conquered the 53rd Dungeon. Caim is the Djinn of Listening Closely and Absolute Sharpness. The Djinn dwells in the long katana which he carries.
- Djinn Equip- Partial Djinn Equip: In this form, he is able to slash his enemies from very long distances with high precision and accuracy. Combined with special swordsmanship of Kina Kingdom, One-Hit Kill Technique (一撃必殺, Ichigeki Hissatsu, "one blow certain kill"), this form becomes deadly.
- Full Body Djinn Equip: Later Takeruhiko reveals that his Djin Caim is a water type Djinn,having been able to conjure gigantic waves of water for his soldiers to ride on in dry land as a means of fast transport in land and later displayed immense water based ability to literally carry the entirety of the Kina Kingdom Island using a giant body of water.
Their relationship is not clear, but Nanaumi seems to worship Takeruhiko, as when he appears on the battlefield she squeals and excitedly calls him "my lord", and adds that she has been waiting for him. Takeruhiko even asks if Nanaumi waited for him there "like a good girl".
His name is likely based on Prince Yamato Takeru of the Yamato dynasty. With the kanji 倭健 standing for Yamato Takeru and 彦 standing for prince.