Practically everyone in this show has some kind of mental hangup, and that’s the focus of the series.
For the three main characters, they all have full-grown psychological disorders that conflict and cooperate at the same time. The male lead Tarou is a masochist, but only when women do the damage; Mio is a sadist and, in classic anime style, is self-conscious about her flat breasts; and Arashiko of the abundant breasts cannot stand being touched or even being around men and will even attack them if they get too close. Therefore, Tarou is in ecstasy when Mio or Arashiko hit him, and they do, a lot, as Mio gets inordinate pleasure from doing so whereas Arashiko does so when flustered or by accident and is immediately sorry.
Its also the running joke, that Mio is always trying to find ways to ‘cure’ Tarou’s masochism (including an candle-lit exorcism) that always wind up reinforcing his masochism instead of curing it. Of course, one of those ways involves hypnosis.
The rest of the cast all have their hangups as well: Tarou’s mother and teen-aged sister are extremely overly affectionate toward him (both want to marry him) and even compete with each other (and his girlfriends) for his affections; Tarou’s friend Tatsukichi is a cross-dresser (and quite good at it) and seems to have an alternate personality emerge when dressing as a woman; Noa, a senior, although her appearance is still that of a younger girl, is a genius who never had a childhood as she had to study all the time, and who always refers to herself in third-person; Noa’s assistant YukinojÅ is a major lolicon (fan of prepubescent girls) and joined the Inventor’s Club to be closer to Noa; and school nurse Michiru knows all about everyone’s hangups, possesses an apparently unlimited supply of cosplay costumes and loves to take pictures of the students in them.
Needless to say, the entire series is NSFW.