Issei Noro and Tetsuo Sakurai met in Tokyo in 1974, still in high school. Two years later they started a band, using a different name for each early gig until a magazine profile forced them to settle on one; Noro's mother suggested picking a constellation, and Cassiopeia became Casiopea. That first 1976 lineup paired Noro and Sakurai with keyboardist Hidehiko Koike and drummer Tohru Suzuki, but both left later that year after an EastWest amateur band contest.

Keyboardist Minoru Mukaiya and drummer Takashi Sasaki joined in 1977, and the band's self-titled debut arrived May 25, 1979, with Randy Brecker, Michael Brecker, and David Sanborn all sitting in as guests. That's before the rhythm section most fans picture first was even in place. Drummer Akira Jimbo didn't join until 1980, replacing Sasaki and completing the lineup that carried Casiopea through its most influential run.

Mint Jams is the record most listeners start with. Recorded live over two nights at Tokyo's Chuo Kaikan Hall (February 23 and 24, 1982) and released that May on Alfa Records, it was named one of the year's best by Japan's own jazz press, including the magazines Adlib and Jazzlife. It's the sound of a band that had spent three years touring together, caught on tape before a live audience instead of smoothed out in a studio.

The lineup kept moving after that. Sakurai and Jimbo left in 1989 over conflicts with their side projects, Sakurai's Shambara and a planned duo, Jimsaku, that the two eventually formed together once they'd left. Bassist Yoshihiro Naruse and drummer Masaaki Hiyama replaced them in 1990; Noriaki Kumagai then replaced Hiyama on drums from 1993 to 1996, before Jimbo returned as a supporting member in 1997, the same year Casiopea, T-Square, and Jimsaku shared a bill at Tokyo Jam. Noro froze the band's activities entirely in 2006, then brought it back as "Casiopea 3rd" in 2012 with Kiyomi Otaka replacing Mukaiya on keyboards, renamed it "Casiopea-P4" in 2022 when Yoshinori Imai replaced Jimbo on drums, and reverted to the original name in 2025 with pianist Jun Abe replacing Otaka. They released a new album, True Blue, in August 2025, and have tour dates booked across Japan and Los Angeles through 2026.

Mint Jams wasn't done being discovered, either. Around 2018, YouTube's recommendation algorithm started pushing the album hard as part of the site's City Pop rediscovery wave, handing a 1982 concert tape to listeners who weren't alive when it was recorded. A limited clear-green vinyl repress followed in 2025.

Casiopea's earliest sound was aimed squarely at emulating Beck, Bogert & Appice's hard rock-funk, before the band settled into the more purely instrumental, jazz-inflected fusion it became known for. Noro summed up the early approach as "thrills, speed, super technique," a catchphrase that stuck to the band even as he later pulled back toward musicality over pure chops. The American guest list on their records places them in direct dialogue with the U.S. fusion and session scene of the same period: the Brecker Brothers and David Sanborn on the 1979 debut, producer Harvey Mason and percussionist Paulinho Da Costa on Eyes Of The Mind (1981), and Los Angeles studio players Nathan East, Lee Ritenour, and Don Grusin on 4×4 (1982).

Casiopea's own influence runs the other direction too. The band is often cited as the reference point for a "Casiopea-like" style among later fusion musicians, and it's credited with helping spark Indonesia's own fusion scene, directly influencing bands like Krakatau, Karimata, and Indonesia 6. Within Japan, Casiopea is most often paired with fellow 1976-founded band T-Square as one of two pillars of the era's jazz fusion boom, Casiopea built around Noro's guitar and T-Square around saxophone, a comparison borne out by how often the two bands have actually shared a stage rather than just a genre tag.