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.

• Madhouse
• Nippon Television Network Corporation
• Ryunosuke Kamiki
• Hitomi Miyauchi
• Mitsuki Tanimura
• Sumiko Fuji
• Ayumu Saito
• Takahiro Yokokawa
• Kiyomi Tanigawa
• Mutsumi Sasaki