Minoru Mukaiya, born in Tokyo on October 20, 1956, was Casiopea's keyboardist from 1977 to 2006 — twenty-nine years, the longest single tenure documented among the band's core lineup in this project's coverage, longer than even founder Issei Noro's own interrupted run. He was succeeded by Kiyomi Otaka in 2012. In 1985 he founded his own company, Ongakukan Co., Ltd., which he continues to lead as president.

His work after leaving Casiopea's day-to-day activity split into two distinct directions. He composed extensive video-game scores for Koei's historical strategy franchises, including Romance of the Three Kingdoms II (1989), Super Nobunaga's Ambition (1992), and Samurai Warriors 2 (2006) — a genre with a devoted following largely separate from jazz-fusion audiences.

Far more widely heard, if far less widely credited, is his work composing train station departure melodies across Japan. He created the Kyushu Shinkansen's station departure sound and vehicle broadcast chime, and the departure sound for the Keihan Electric Railway. Over May and June 2015, he wrote new departure melodies for nearly every station on Tokyo's Yamanote Line loop, one of the world's busiest urban rail lines. As of 2024, he is credited with more than 200 unique melodies spanning over 110 stations across Tokyo, Kyushu, and the Tokyo Metro network — functional, everyday music heard by millions of commuters who have no idea a jazz-fusion keyboardist composed it.

He remains an active performer: alongside Tetsuo Sakurai and Akira Jimbo, he now plays in the Katsushika Trio, a group initially built around revisiting the 1980s Casiopea material he helped compose the first time around.

Mukaiya's career spans an unusually wide range of "invisible" composing work — historical strategy video-game scores and functional station-chime music — alongside his more conventional identity as a jazz-fusion keyboardist, reflecting a career-long interest in music that serves a practical, everyday function as much as a purely artistic one.