Ōishi has performed theme songs for Overlord (all three seasons), Hand Shakers, Ace of Diamond, Ace of Diamond: Second Season, Prince of Stride: Alternative, and SSSS.
As a solo artist he has performed theme songs for Monthly Girls’ Nozaki-kun, Tada Never Falls in Love, and Cop Craft.
He also composed and arranged theme songs for Makura no Danshi and A3!
Ōishi had announced the surgery and one-month hiatus last April, but delayed the surgery because of the state of emergency declared in Japan due to the new coronavirus disease (COVID-19).