Sado Tarou suffers from sexual masochism; he experiences sexual pleasure from pain. He falls in love with a certain girl, Shihori, but decides he cannot pursue her with his condition. His best friend, Tatsukichi Hayama, tells him to visit the Voluntary Club, a place that grants students' wishes, for a cure. At the club, he finds Isurugi Mio, a girl who thinks she is a god. She pretends to be nice but as soon as Tarou tries to leave, she turns into an evil monster telling him that she was being patient. He also sees Arashiko Yuno, whom he apparently has known before in middle school, the girl who was actually responsible for his masochism. Later, Mio decides to continue his treatment by giving Tarou so much pain, his mind will no longer feel any pleasure. She injures him so he must stay in the infirmary where Yuno looks after him.

In the second episode of MM! we’re given a larger picture regarding the connection between Yuuno and Tarou. Yuuno, Tarou’s middle school friend, is the one that caused the sexual masochism fetish that he has right now by slapping him in back in middle school.

In this episode, the show starts again from last episode, where a new character appears. Her name is Mamiya Yumi, she’s Arashiko’s best friend and a creepy pervert who’s an expert at massaging people (and giving them orgasms… derp 0-0). As we meet her, she tells Tarou that Arashiko is going to transfer to an all girls school with her. As Mio is trying to tell him that he should probably care about this transfer, we see a flash-back of the scene where Arashiko tells Tarou how she became androphobic, and we learn some extra info concerning this topic. The next day Yumi comes to the Volunteering Club in order to meet everyone, and a very funny scene occurs where everyone’s weakness is pointed out.

The entire episode follows Tarou and Mio on a pseudo-date, where they have to do lovey-dovey couple things together, in order to cure each other's (Tarou's masochism, Mio's socialization issues). I found it absolutely hilarious how Tarou constantly received phone calls from Michiru-sensei, giving him instructions on what to do.

Episode 5 starts off with Mio in a witch costume performing an exorcism on Tarou. In the distance, Noa Hiiragi is spying on Tarou while she wears some kind of supercomputer eye display and seems to be calculating some kind of power that's being emitted by Tarou as he endures Mio's treacherous torture.

Episode six starts off with more training with Mio, to help cure Tarou's masochism. Not long after their training, I nearly got a nosebleed just by seeing Arashiko in a nurse uniform.

The members of Second Voluntary Club and some other friends have come to the beach for the “intensive training camp”. While Taro and Arashiko get closer to each other, a mechanical shark emerges and kidnaps them to the offshore island.

Hypnosis is a new method Mio came up to cure Taro’s masochism. Her hypnosis appears to have worked on Taro at first, but now he has completely different issues and they’re all as bizarre as his old issue.

Sakuramori Festival is here! The Second Voluntary Club will set up a “trouble-shooting booth” to solve people’s issues. Taro and Mio sit in the booth, but no one comes.

Taro notices a sudden change in Arashiko’s behavior. She’s no longer sweet and shy, but now bossy and mean just like Mio. Taro wonders if Mio has said something to Arashiko for her to act so erratically, but accusing her only results in harsh punishment.

Lady Mio’s very sadistic treatment for Taro’s super masochism is now in session. As he begs for more beating from Lady Mio, he accidentally slips and knocks himself unconscious for a second. He gets up but he doesn’t remember anyone who’s around him.

The Second Voluntary Club members are setting up Christmas trees so that students can hang strips of papers with their wishes. However the most of the wishes are unrealistic and unachievable.