Twenty-three-year-old Masamune Kazama spends his days working a mundane office job and dwelling on the past. Although it has been five years, the young bachelor continues to hold onto his relationship with his past girlfriend, Youko Tsukamoto.

Out of the blue, he receives a call from Youko's mother, who informs him that she has passed away in an accident. Furthermore, he learns that Youko has left him with a young daughter, who was raised in secrecy overseas. Stricken with grief, Masamune decides to take in the young girl and raise her on his own.

My Girl is a tale of family, loss, and acceptance as Masamune navigates the complexities of daily life as a single father.