Tsuma, Shougakusei ni Naru.

妻、小学生になる。

Keisuke Niijima has lived in grief since his wife, Takae, passed away 10 years ago. But when a young girl visits, claiming to be Takae reincarnated, Keisuke and his daughter, Mai, are drawn into a miraculous reunion. As the girl reveals intimate details only they could know, the Niijima family slowly begins to heal, rediscovering love and warmth in the most unexpected way. (Source: Crunchyroll)