Mesudachi tells the story of two childhood friends who live in a village with very few inhabitants. Satsuki, a sociable and not very feminine girl, has been with the main character since childhood. One day, when she comes to visit him, she finds several pornographic magazines there. After that, she wants to do the debauchery that she spied on in the magazine, but the main character tries to avoid her. When her little femininity is trampled, she decides to seduce him by provoking him in the most perverse ways that even her friend would not be able to ignore, and in the end they still have sex. Mesudachi EX picks up a month after everything that happened in Mesudachi. Childhood friends bonded and now have sex everywhere. This time, they decided to do it at school, but they were discovered by the student council president, who did not stop them, but waited until they finished and dispersed. As soon as the couple separates, the protagonist is knocked out with a stun gun. After some time, he wakes up bound on the floor, and then is raped by the president, who is in a yandere state.