Tomo-chan is a Girl! Vol. 1 by Fumita Yanagida

Boyish high school girl Aizawa Tomo finally manages to tell her childhood friend Jun that she's got a crush on him. Unfortunately, her confession goes right over his head - he didn't even realise she was a girl until middle school, and even now, Jun still thinks of her as a bro! How can Tomo-chan possibly convince him otherwise and win Jun's heart?
Binding: Paperback / softback