Bleach: Jigoku-hen

Masked Hell denizens appear in Karakura town so Rukia and Renji are sent to investigate the matter. After a fight with them they manage to rescue Karin(Ichigo's sister) from them but they return to hell with Yuzu(also Ichigo's sister). Having rescued Karin, Kokuto(a hell denizen himself) befriends Ichigo and they set out to save Yuzu from Shuren(the commander of the denizens that kidnapped Ichigo's sisters). (AnimeNewsNetwork.com)