This one is so interesting in some ways. The story starts off with three people in an open poly kinda relationship with one of them having a girlfriend. (Again Mao the one with the girlfriend must also be in a poly or open relationship with his girlfriend.) It's hard to decide the boundaries of the respective relationships. Because it's clear that they only really have sex with each other like a fixed pairs poly relationship, but two of the people desire monogamy. However soon these boundaries become established and it just becomes a light drama with some fluff and kinda fizzled out for me at the end.
Chika-chan to!