Masato Kadowaki (門脇 将人)

A former friend of Arata in middle school, where they both were on the track team. In high school, he and Hinohara have the same class. He hates Arata Hinohara because he believes that Hinohara looks down upon him, and constantly bullies Hinohara. He causes everyone to turn against Hinohara, including his best friend.

(Source: Wikipedia)