Kaji is in the same grade as Ayu and Nina, and is also the school idol. He is considered cool and always has a nice smile. All his fans are constantly giving him presents, and he even has admirers from the 3rd grade. However, this is only his outer mask. Kaji is in reality a normal guy who hates being given presents by people he doesn't know. But he is working hard on his "nice person" persona because the girl he likes, Ayu, once told him that's the way she liked him.

He becomes closer to Nina after she discovers his deception. He is an introverted person, and doesn't like giving away his real feelings or thoughts.

Kaji belongs to the school's baseball club. His best friend is Tsujiai.