Shishunki no Iron Maiden

Childhood friends and neighbors, Mayama Haruki and Himemiya Tsukiko were the best of friends until, in fourth grade, a girls only meeting caused Himemiya to shun and and avoid Mayama. Now second year middle school students, Mayama is an ero-freak, who likes to taunt and pick on girls, while Himemiya is a straight A honor student. But the distance between them closes after Mayama discovers Himemiya's secret, and the secret behind the mysterious girls only meeting. Now Mayama is forced to help hide Himemiya's secret as she tries to make sense of it all.