Naotaka Natsume  

Nao-kun, 夏目 直貴

The older brother of Tomoharu, whose identity remains uncertain due to his absence from the show for several years. His image appeared in the third season's third episode when Tomoharu faced danger. He was deceived in order to appear in the seventh episode, but ultimately met a tragic end when he was shot by the Koala's owner and passed away.