Chapter 58 of the Jigokuraku manga.
After his parents were killed and being brought in by the Yamada clan, a young Shugen talks to Eizen about taking on the duty of an executioner. Shugen tells Eizen that he fails to see the logic in the Yamada clan's way of executing criminals with no pain or emotion and wonders why they can't give criminals a painful death since he believes that they deserve it. Eizen explains that such an act would defile the execution grounds and tells Shugen that he is here for him to make sure he is a well suited executioner by riding him of his hatred. He then tells him that he looks forward when he could see that he has become a "glorious blade". In the present, Shugen mourns Eizen's death and makes the decision to lay his soul to rest before moving forward. While giving him a proper burial, one of the ninja takes note of the four Asaemon's behavior and plan on using the dangers of the island to outsmart the Asaemon and complete their mission in killing Gabimaru. The group is then attack by a horde of Mōnshin that are commanded by a Dōshi to capture the humans on behalf of Lord Tensen. While still mourning Eizen's death, Isuzu and Kiyomaru protect Shugen from the Mōnshin's attacks on him. The genin also assist in bringing down the Mōnshin as well. After finishing reciting his sutras, Shugen cuts down a Mōnshin that attempted to attack from behind. He then uses its staff to repeatedly damage his blade given to by the shogun and swears vengeance against all that resides on the island.