Nanashi no Asterism

Nanashi no Asterism summary:

Tsukasa Shiratori, Nadeshiko Washio and Mikage Kotooka are three close-knit friends in junior high school. For almost a year, Tsukasa has been harboring a secret she can't tell anyone: she has a crush on Nadeshiko. She resigns to keep it locked away forever, but then discovers that Nadeshiko has a crush on Mikage. Not wanting to mess up their current relationship, Tsukasa decides to support Nadeshiko in any way she can. However, Mikage has a secret of her own that she can't share with anyone.