Ikkaku, Hanatarō Yamada, Nanao Ise and Hōzukimaru are sent to investigate some thefts that have taken place and track the culprit to the sewers. They are attack by a large monster, which manages to injure Ikkaku. The rest discover a white robot, who has the stash of stolen items. The large monster, revealed to be a tentacle sword beast, attacks the group again. The robot heals Ikkaku and fires a powerful blast at the tentacle sword beast, destroying it. It is revealed that the robot is Hanatarō's zanpakutō, Hisagomaru, which had resisted Muramasa's control because it did not resent Hanatarō. The group returns the stolen items, but Hisagomaru was separated from the group.