Yasushi Ishii (石井 妥師, Ishii Yasushi, born 10 March 1970) is a Japanese musician from Utsunomiya, Tochigi Prefecture, Japan. He specializes in experimental, jazz fusion and hard rock. He is famous for his work with anime scores. He composed music for and scored the first Hellsing anime, with the music released as two separate soundtracks. He also was the voice for the Intelligencer in the video game Chaos Legion.In 1991, he debuted as a composer for Epic Records Japan, and started composing music for Misato Watanabe, Takashi Utsunomiya, and went on tour with the band T.utu with the Band. It was at this time that Ishii changed how he wrote his given name from (恭史) to (妥師), though the pronunciation stayed the same. In 1994, T.utu put out their first album, and Utsunomiya, as one of the members of the former members of T.utu, split off into another band named Boyo-Bozo which Ishii also helped compose music for. After Boyo-Bozo broke up, Ishii composed music for a number of other artists including Lazy Knack, Tomoe Shinohara, Masayuki Suzuki, and V6.