Ona Ken! 1.4 -Tabi no Haji wa Kakisute-

Nao Kasukabe is a well known troublemaker at her school.
Mako and Tsuyutani share the limelight as the main characters.
In the story, Mako carelessly ends up the victim (?) of her naughty friend. Haha.
At this rate we'll end up doing spinoffs for every decimal until Ona-ken! 2.0.
That's really up to you!

Welcome to Ona-Ken!, the adventure story about girls who form a masturbation club.

[From DLsite English]