She is an elementary school girl who believes in Yokai. This year, she went to her grandpa's house to play in the river! Her grandpa told her, "Be careful, there are Kappas in that river." And then she saw it... something jumping into the river... "That was a Kappa..." Then Guest said, "Kappas don't exist..." A week later, she stormed in! And she brought a university professor with her!? "Hey, Guest, do you still have an argument after this?" The debate with the elementary student begins...

A university professor majoring in folklore. For the sake of his relative, Kana-chan, he held a "Kappa Legend and Folklore Basics Lecture." "I will judge fairly and impartially." "Once 'Ref, Judgment' is declared, I will determine which side was more persuasive." However, the Professor looks at Kana-chan with gentle eyes... The truth is, the Professor also saw a Kappa long ago. That's why he pursued the path of folklore. He might be seeing his younger self in her...