Haira has two shapes he can assume: a grotesquely obese form (which he favors, believing it to be good-looking) and a slim handsome one, which is actually much more powerful, that he assumes when he gets serious. Like the other berserkers, Haira is a cannibal, and all he can think about is food. He forces his victims to play word games with him, with the loser of each round getting assaulted by the winner. He initially got the better of the confused Bontenmaru, but he was eventually forced to change into his handsome form. He was killed after a fierce battle when Bontenmaru unleashed his full power. Haira's attack is called "union core."