Grey Shadow, the Secret of the Dolls

As Koga tells Dalk to finish Ichigo off, he is reminded of Cain, a young Bount he once mentored. In a flashback, Koga remembers when he first met Cain, and taught him how to summon his doll and live with another Bount. However, the doll Cain created was too powerful for him to control and destroyed him, an incident Koga continues to regret.