[GrimZata]

Kurokage and Gridon were ganging up on Kaito, it was an unfair match, and Kouta wasn't going to stand around and let that happen, just because he's a good guy, doesn't mean he's on a moral highhorse. He did what he thought was right, and it's pretty clear Kouta isn't the kind of guy to think about consequences.

Also, why does everyone seem to be thinking Kaito is just some ultimate bad guy stuck in a kid's game? For one thing, the people in the game pretty clearly don't think of it as a kid's game, only the people outside of it do, even if they're the ones who are more or less right. Which also helps to justify Kouta's reasoning, he doesn't think of their battle as just kids playing around, I mean they're using lethal weapons against each other. Another thing is, Kouta seems to realize that Kaito isn't actually that bad a guy, he's got a good heart.