Known as one of the biggest names in the soundtrack world, he has worked on a wide range of mixed media productions, including anime, TV shows, films and video games.

[1] Among his credits are Toei's Kamen Rider Heisei Generations Forever, Tsui Hark's Seven Swords and Young Detective Dee: Rise of the Sea Dragon; Wilson Yip's Ip Man; Mamoru Oshii's films The Red Spectacles, StrayDog: Kerberos Panzer Cops, Ghost in the Shell, Mobile Police Patlabor, the OVA and TV anime adaptations of Vampire Princess Miyu, The Sky Crawlers and Avalon; the anime adaptations of Rumiko Takahashi's Ranma ½ and Maison Ikkoku; the live-action adaptation of Gantz and Hideo Nakata's films Ring, Ring 2, Chaos, Dark Water and Kaidan.

With a few friends, he created the band Muse, playing fusion rock and participating in music competitions.

[2] After leaving Muse, Kawai began composing music for commercials in his home studio.

Kawai has worked on several projects with director Mamoru Oshii (both Headgear members) and has written scores for all of Hideo Nakata's films.