Kaidou of the Beasts, renowned as the world’s “Strongest Creature” is the Governor-General of the Beasts Pirates and one of the Four Emperors ruling over the New World. He is also the father of Yamato.

From his base on Onigashima, Kaidou has occupied Wano Country along with his crew and once allied with Wano’s shogun, Kurozumi Orochi, until Kaidou decided to dispose of him for his New Onigashima Project. Decades ago before the formation of his own crew, Kaidou was an apprentice in the legendary Rocks Pirates, where he ate the rare Mythical Zoan fruit, the Uo Uo no Mi, Model: Seiryu. He is currently in an alliance with his former Rocks crewmate and fellow Emperor, Big Mom.

Kaidou was first referred to by Monkey D. Garp in the Post-Enies Lobby Arc and then directly mentioned by Gecko Moria in the Thriller Bark Arc, with his status as one of the Four Emperors revealed after the Straw Hat Pirates defeated Moria. Thus, Kaidou is the third Emperor mentioned by name and the last to debut. Before he debuted in person, his voice was heard in a flashback that Kozuki Momonosuke had when first disembarking on Dressrosa.

He is the primary antagonist of the Wano Country Arc and one of the central antagonists of the Four Emperors Saga.