Read manga: Dramatic Irony (Namaco)

manga
Summary:

Can you give me a happy ending? Komatsu Risa is in love with her childhood friend, Sano Chihiro. Although they have a very close relationship, and are often mistaken for a couple, Chihiro is unaware of how Risa feels and accepts a confession from another girl... Heartbroken about her first love, she confides in her seemingly indifferent homeroom teacher, Natsuo.