Akizuki-san wa Otona ni Narenai

The story centers on Yusa, a 25-year-old nursery school teacher. Yusa's boyfriend is Akizuki, a 32-year-old president of a toy company. Akizuki is handsome and capable, but he unfortunately still behaves in childish ways. When they begin living together, their everyday lives become more and more strange.

(Source: AnimeNewsNetwork)