Teenage math whiz Kenji Koiso agrees to take a summer job at the Nagano hometown of his crush, Natsuki. When he arrives, he finds that her family have reunited to celebrate the 90th birthday of their matriarch. His job: pretend to be Natsuki's fiancé. Meanwhile, his attempt to solve a mathematical equation causes a parallel world's collision with Earth.
Kenji Koiso (voice)
Natsuki Shinohara (voice)
Kazuma Ikezawa (voice)
Sakae Jinnouchi (voice)
Wabisuke Jinnouchi (voice)
Takashi Sakuma (voice)
Yukiko Shinohara (voice)
Kazuo Shinohara (voice)