Ryōtarō Okiayu

In Demon Slayer: Kimetsu no Yaiba, produced by studio Ufotable, Okiayu provides the Japanese voice of Kokushibo, the most senior of the Twelve Kizuki and one of the series' most formidable demons. The character suits the lower, commanding register for which Okiayu is known, a voice he has applied across decades of prominent antagonists and authority figures. By the time he took on Kokushibo, Okiayu had been working steadily since 1989, making the role a late-career addition to one of the most extensive resumes in Japanese voice acting. His participation continues a pattern of casting in high-profile shonen adaptations, a field in which his name has long been familiar to audiences.

Active since 1989 and affiliated with Aoni Production, Okiayu has voiced a broad gallery of leading and supporting characters across anime, games, and dubbing. Among his best-known parts are 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, and Toriko in Toriko. His video game and adaptation work includes Alucard in Castlevania and Zero in Mega Man X, while romantic and dramatic titles add Yuu Matsuura in Marmalade Boy, Shigure Sohma in Fruits Basket, and Dark in D.N. Angel. He also serves as the official Japanese dubbing voice for Scott Foley, Taylor Kitsch, Lin Gengxin, and Stephen Fung.

Beyond voice acting, Okiayu has pursued music, performing as a member of the Entertainment Music Unit from 1995 to 2000. His vocal range spans A to E sharp, and he speaks with an Osaka dialect. He is married to the voice actress Ai Maeda, and his older sister works as an animator. The combination of acting, singing, and steady dubbing assignments has kept him among the recognizable veteran performers of his generation.