Chapter 57 of the Jigokuraku manga.
After being warned of another party’s arrival on the island, Shion believes that it is Shugen and the other Asaemon who were sent as reinforcements by Eizen. Fuchi also tells them that another group of criminals were to accompany them as well. Gabimaru asks Sagiri if Shugen is a potential ally. Sagiri vouches for him and says that his strength will be helpful for the group, however, Gantetsusai doubts her statement if Shugen is unable to use Tao. Shion confirms that Shugen is able to perceive Tao since he taught him in the past. While at the coast, Shugen confronts a Sōshin and easily defeats it barehanded using the knowledge of anatomy he acquired from Fuchi and his understanding of Tao by Shion. Although Nurugai is impressed with his strength, Yuzuriha mentions about a story that made Shugen infamous. Sagiri explains the story of how Shugen executed the captured members of the Silver Serpent yakuza group in order for their leader to reveal the remaining members. The group becomes concern but Sagiri reassures them that Shugen is kind deep down, leading Fuchi to state that Shugen was Sagiri's first crush. Sagiri denies this claim and explains that she merely admires him due to his involvement in her earning a ranking in the Yamada clan. After killing a group of Sōshin, Isuzu and Kiyomaru come to his aid but Shugen reassures them that as their senior, he will take on the responsibility of taking care of lesser matters like fighting the monsters. While Sagiri believes that Shugen will come to their aid, Shion disagrees and reveals the full story of how Shugen not only executed the entire Silver Serpent group but also their families since they were connected to each member. Shion explains that Shugen despises criminals and would not think of allying with them or have any Asaemon to be involve with them as well. As Shugen's group travels, Shugen becomes shocked to see the corpse of Eizen.