Yoshinori Imai, born November 2, 1987, in Kanagawa, began playing drums at fourteen under the direct influence of Akira Jimbo. He studied under Yasushi Ichihara and Kozo Suganuma before establishing his career, and became a Zildjian artist. When Jimbo left Casiopea in 2022, Imai joined as a full member on July 1 of that year, taking over the drum chair of the musician whose playing had drawn him to the instrument in the first place — the band's fourth lineup era, known as Casiopea-P4.

His Casiopea discography runs from New Topics (2022) through Right Now (2024) and a 2025 release titled P4's Finale Sound Version; subsequent credits in 2025 and 2026 (True Blue, Miracle Night Live) appear under the plain Casiopea billing, suggesting a further lineup transition not independently confirmed beyond the billing change itself. He is also a member of the band UK Rampage.

Outside Casiopea, he has built a substantial parallel career as a session drummer for video-game and anime soundtracks, working under a rotating cast of lead composers rather than any single regular collaborator — the Octopath Traveler soundtrack series (2018, 2021, 2023), Tetris Effect (2020), a Danganronpa remix collection (2021), Star Ocean The Second Story R (2023), and Rain Code (2023) among them. He has also recorded with singer May'n and vocaloid/electronic producer sasakure.UK.

Imai's playing carries forward the technical, high-energy fusion style associated with his direct predecessor Akira Jimbo, while his soundtrack session work demands a more varied, genre-flexible approach suited to scoring rather than a fixed band identity.