Watashi ga 15-sai dewa Nakunattemo.

While being estranged by his daughter and being blamed by his wife, middle-aged office worker Iwashita lives modestly in his own way. That is, until he met Shiina, a girl who suddenly appeared one day in front of him. She then approaches Iwashita as a "customer" for "a 20,000 yen meal". This story of a small escape begins with a painful and dazzling 15-year-old girl seeking her own value and a 40-year-old middle-aged man struggling between reason and desire.

(Source: Funguild, translated)