Source https://www.pixiv.net/en/artworks/105626775

In order to fight against enemy kunoichis, the student ninja girls must learn the secret ninja art of the nyoninboh - a fearsome secret technique which is able, by channeling ninja energy, to tranform a girl clitoris into a big, fat cock. Very few kunoichis are able to resist its power.
The master bring an old scroll, which is said to contain the secret technique, to the classroom.
Quickly, curiosity turns to mischief as the girls become eagier to try the new technique on each other, and the situation goes out of hand as the academy grounds is engulfed in yet another pink whirlwind of debauchery and the girls try to make each other cum in their pursuit toward mastery of sexual ninja arts.
At the same moment, a pair of mischievous twin kunoichis from a rival ninja school make their way into the academy to challenges the girls into sexual combat. In spite of being highly confident in their sexual skills, those two naughty little girls are going to be taught a lesson the hard way as they become the targets of all the kunoichi of the school who want to relieve their raging cock...