Yōto Yokodera is a second year High School student who is arguably the biggest pervert at school. His problem is that he is not good at showing his real emotions. One day, his equally perverted best friend completely transforms and gets rid of his “impure thoughts”; a feat he attributes to the power of the statue of "warawanai neko" (the cat that won’t laugh). As the rumors suggest, by wishing upon the statue and giving an offering (e.g. stuffed animal, etc.) you can wish to remove a personality trait from yourself that you do not wish to have anymore. What they do not realize at the time is that it will remove the unwanted trait and give it upon to someone who does need it. As he’s making his offering to the statue, a girl (Tsukiko Tsutsukakushi) arrives at the same place. Tsukiko also hearing of the rumors of the warawanai neko, was there to make her wish. She wishes to be able to be more like an adult and not show her emotions so easily. Both of them wish upon the warawanai neko and to their surprise the next day at school, Yōto is unable to tell a single lie, and Tsukiko is unable to show any sign of emotion whatsoever (aka kūdere). After realizing that they do not like the change that happened, they work together to try and find out who has received their trait that was taken away in order to get it back, bringing in another character into the mix, Azusa Azuki, an ojōsama type girl who is the most beautiful first year that has just transferred. She is always being confessed to by many boys in school, the odd thing is that she has no friends and is always alone. Yōto finds out that Azusa is the one that received his unwanted personality and that is where the love triangle and plethora of problems begins.

The "Hentai" Prince and the Stony Cat. (変態王子と笑わない猫。 Hentai Ōji to Warawanai Neko.), also known by the shorthand HenNeko (変猫。) and Towanai (とわない), is a Japanese light novel series written by Sou Sagara and illustrated by Kantoku. It was adapted into a manga series in 2011 and an anime television series, which premiered on April 13, 2013.