Koji

A 6th grade boy who goes to the same school as Yuna. He is like a brat. However, for some reason, he can't go against his little sister Piko, and there are times when he goes out with him selfishly. He has a lot of worries about it. He's pretty good at computer games. Apparently he's learning ''combat karate'', but he's still a white belt (and therefore weaker than Yuna). His secret hobby is to record his feelings in his diary. In the second season, he falls in love with Sae and Zuruko.