It's Toshishita Jidai

Aoi is a member of the astronomy club at her high school and has wanted to tell her feelings to Egawa, a senior about to graduate, but has not been able to. Her emotional struggle ends when she hears something hurtful from the other person, leaving her feeling down. Her younger childhood friend Shintaro then comes into her life. As a loud and playful junior, he both amuses and irritates her.