In a not-so-distant future, Okamura Aya, also known as 'Aachan', embarks on independent living after landing a new job post-graduation. With her mother away working as a doctor overseas, Aachan's Proud apartment now houses only her father and the aging cat, Mii-san. Despite her father's attempts to connect since her departure, a palpable distance lingers between them. As Aachan reminisces about the joyous moments shared with her parents and the solace Mii-san provided during her mother's absence, a phone call interrupts her reflective night.