The Guy She Was Interested In Wasn't a Guy at All Vol 4

From the Yen Press edition

Prom night starts off with a bang! Mitsuki’s made a snap decision—she’s ditching the industry party and joining Aya at the dance. Aya said she wasn’t going, but if Mitsuki wants to mend the growing rift between them, she’ll have to take the chance. As their final year of high school draws to a close, the two have no choice but to face each other and their feelings. Will they be lifelong friends…or something more?

Source: Yen Press