"GS Wonderland" is about the 1960's Group Sounds bands - A Japanese pop movement inspired by the Beatles and other mid-1960's Brit Pop. Three young men set out to start their own band "The Diamonds" when they are signed to a recording contract during their very first rehearsal. Things turn for the unexpected when their agent brings Mick (Chiaki Kuriyama) into the group as their keyboardist.
Miku Ohno

Masao Kigawa

Shun Masamiya

Kenta Kashiwabara

Ryosuke Kajii (agent)

Tajio Hasegawa

Taeko Ishinuki

Kyoichi Kumada

Kenichi Kamata

Tomonori Sasaki

Jukichi Matsuda

Chief

Atsushi Momose

Chorus

Chorus

Unknown Role

Unknown Role

Director of record company

Muneo Ohkouchi

Akemi Ishinuki