Three former middle school friends who reunited after 37 years to pursue the mystery behind their former club advisor's disappearance.

Takashi Sorimachias 'Yun' Yuta Yoshii
Nao Omorias 'Chen' Hajime Fujimaki
Kenjiro Tsudaas 'Kinpo' Kisuke Kikuhara
Mai Kiryuas 'Matilda' Michiru Miyashita
Riko Fukumotoas Hakuba Nishino
Noritaka Hamaoas Tsurumi
Yuki Matsumuraas Kento Yoshii
Noriko Nakagoshias Satsuki Onodera
Keiko Takahashias Shoko Kikuhara