"You've escaped from all your suffering, so I'll make sure you know happiness for the rest of your life."

Shiroshika Muku's childhood ended ten years ago when her father died, her best friend moved to Tokyo, and she, together with her mom and little sister, had to go to live with her grandparents. Trying to fulfill the role her father left behind, Muku, a now 21-year-old woman, feels like drowning.

She needs to care of her grandfather, who has dementia, and find a new job after the company she started working for after graduating high school went bankrupt, so she can pay her grandfather's medical expenses and the school expenses of her little sister. She also needs to help her mother with the housework and listen to how her grandmother tells her she is not good enough simply because she is a woman, as well as the importance of having a man around.

She needs to run away and live her life for herself before she starts hating the family she loves so much, but with nowhere to go, this seems impossible. That is, until her childhood friend Yuto returns after ten years, on a snowy day...