F-Ken (manga)

F-Ken (Fけん) is a Japanese manga series written and illustrated by Yuusei Matsui in the Weekly Shonen Jump magazine.

Plot
Fuji's high school kendo team has an embarrassing losing streak, but things start to turn around as they suddenly begin winning most of their matches and even qualify for nationals. The secret is the arrival of their new team manager, a girl who uses her perfect looks to seduce the members of Fuji's kendo team. The manager manipulates the boys by taking advantage of their sexual fetishes, implying that she is willing to indulge their desires in order to unlock a monstrous potential in their kendo abilities. Fuji stands against this immoral method, but he comes to learn that there may be more to his manager than he first thought.