What kind of animation is this?

This is the Tenure Faculty of Dongchuan University on the High Seas. The characters are Hiromatsu Rijing, Toda Shanquanzi, Dickinson Feather, and Noya Yishu (male owner) in turn.

The story tells that Ichiki Noya, a freshman enrolled in Hailao Sakagawa University, looked for an activity classroom in the astronomy department around the school in order to enter the astronomy department she always wanted to attend as soon as possible, but the classroom was located in the basement for some reason. When he stepped in, what was waiting for him was indeed the "Tianmen Department" with the same pronunciation as the "Astronomy Department", and the girls gathered here as members of the department were all keen on staying at home.