Due to a kappa's careless mistake, Yuuka's common sense and sexual reasoning broke out of her mind into fragments and were scattered all around the world... but by strange coincidence, a mortal from the nearby village just happened to be there and as consequence, he was forced to explain what happened...

The pieces could not be seen with the naked eye and yet the mortal could... so he was forced by Yuuka to help collect the pieces in order to regain the fragments of her mental mind but there was one slight problem...

The fragments were very delicate and easy to break, and if they did then Yuuka's common sense and sexual reasoning will be lost meaning her plump body will be for anyones taking...​