[6] His major roles include Byakuya Kuchiki in Bleach, Treize Khushrenada in Mobile Suit Gundam Wing, Hisashi Mitsui in Slam Dunk, Meisuke Nueno in Hell Teacher Nūbē, Kunimitsu Tezuka in The Prince of Tennis, Alucard in Castlevania, Zero in Mega Man X, Yuu Matsuura in Marmalade Boy, Shigure Sohma in Fruits Basket, Dark in D.N.

[3] He is the official voice-over dub for Scott Foley, Taylor Kitsch, Lin Gengxin and Stephen Fung.

[10][11] His father had worked at a movie company for a time before Okiayu was born, and he would sometimes get anime posters and cels from his old colleagues.

[2] His first work in anime was as a Bodkin archer in Dragon Quest[15][16] and his first regular role was as Franz Heinel in Future GPX Cyber Formula.

He said that Nūbē was the culmination of his career and that he was able to put himself fully into the role[17] and play it naturally because he was close to Meisuke's age, and he said he cried when he heard it was over.