Struggling high schooler Miyui Mashio is transported back to 1991, where she attends school with her quarreling parents—realizing she must form an idol group with her mother to help her parents fall in love, or risk never being born.

Mio is 20 years old. Having lost her parents early, she and her grandmother run a traditional inn in Nagano. However, her grandmother gets sick. Mio moves to Tokyo and lives with her father’s best friend, Kyosuke. He runs a public bath. She begins to work at the public bath, but it is scheduled to be demolished to make way for redevelopment.