Aoharu x Machinegun

Hotaru Tachibana, a female high school student, is often mistaken for a boy. She finds herself pretending to be a boy while playing Survival Games with Masamune Matsuoka, who is a host, and Tohru Yukimura, who is an ero-manga artist. Due to certain events, she cannot reveal that shes a girl. The story progresses as she learns to love the sport while battling with her fears of her closest friends finding out shes lying about her gender... (imdb)