This small room was our paradise.
Itsuki lost his grandmother, his only immediate relative, when he was a baby. After that, he's been living with Miduki, who is 16 years older than him, in a dilapidated apartment for 23 years. Itsuki has been suppressing his unrequited love for Miduki since his childhood, thinking this parent-and-child relationship would continue forever. However, the apartment will be demolished soon, and the danger of this cohabitation coming to and end is looming...?!