I ended up giving Kohaku his own gallery because I couldn't figure out whether to put him in amongst the heroes or the villains. Under Naraku's control he does some of the most evil things in the series, such as murdering his own parents. Yet when he recovers his own will he chooses to remain near Naraku -- in mortal danger -- in hopes of defeating him.

In the end I decided that Kohaku deserves his own gallery for being at least a part-time Harmless Looking Villain.