The story is set "slightly in the future" and revolves around Aya "Aachan" Okamura, a woman who has been working for two years and has begun living on her own for a job opportunity. With Aachan's mother working overseas as a doctor, Aachan's father is now living alone with the family's longtime pet cat Mii-san. One night, Aachan returns from a long day at work, and as she rests on her bed, she reminiscences about the times the family had together. She remembers the sadness she felt when her mom went overseas, and the solace she felt when her father brought home Mii-san to give her comfort. Then, she receives a phone call...