B-Bomb is a "bad boy" most of the time. But when he sees a red cat he takes it in, not knowing that it is one of the few shapeshifters that live among them. 

The shapeshifter is U-Kwon, a boy that's last mission is to cause trouble. He finds out that B-Bomb isn't as bad as he seems and starts to fall for him. 

And maybe B-Bomb is falling for him, too.