Born in Osaka, Japan, Sasai began his musical career at the age of 15, playing instruments and forming a band.
[2] His debut as a video game composer came with Crystal Software's Mugen No Shinzo III in 1989 with Chihiro Fujioka.
[2] After sending his demo tapes and résumé to every software house and game company listed in the PC-specialized magazines, he got one response from Micro Cabin.
[1] In 1991, after Square hired Fujioka to be a director, Sasai was invited to join the company as they needed composers to assist Nobuo Uematsu and Kenji Ito.
[2] After a hiatus during the peak of Action's activity, Square assigned Sasai as the sole composer for the Japan-exclusive game Rudra no Hihō (1996).
[1] Sasai's Bushido Blade 2 soundtrack consists of hard rock music and traditional Japanese instruments and harmonies.
[2] Preferring the musical genres heavy metal and alternative rock, his favorite bands are Extreme, Judas Priest, and Red Hot Chili Peppers.