Puberty, An All Boys School!? And Nakano-Kun

Puberty, An All Boys School!? And Nakano-Kun summary:

Hajime Nakano is forced by his mother to enroll at a newly opened all boys high school, and he laments over having to spend the next three years surrounded by other guys. However, he doesn't know that all of the other students are girls secretly pretending to be guys, and each of them think they are the only girl in the whole school.