Chapter 90 of the Jigokuraku manga.
After encountering Shugen, Gantetsusai tries to see how he should go about attacking him, however, Shugen, sees through his intentions and silences his him, telling Gantetsusai that he only wishes to speak with Fuchi. Gantetsusai questions as to who Shugen is since, unlike the other opponents he has faced, he is unable to exploit a blind spot from him. Shugen yells out to Fuchi to explain the reason why his criminal's hands are untied. Fuchi explains that the Asaemon had no other choice but to ally themselves with the criminals due to the extreme circumstances they were all in. Shugen hears his reason but tells him that now that he is here he no longer has to be by Gantetsusai's side, telling him that he does not have to throw away the memories they spent together and the path he has chosen in anatomy. Fuchi says that he also cherishes the times he spent learning about life through his dissections but also says that he did not understood the value of life until the death of his comrades and moves on to explain that they all need to focus on escaping the island. After drawing out his sword, Shugen is shocked to have noticed that Fuchi used his tsuba as Gantetsusai's eyepatch and becomes furious. He is then approached by Gantetsusai who becomes dissatisfied with Shugen in thinking that he will be able to kill him. Gantetsusai clashes swords with Shugen and manages to knock him off his feet, however, he sees him fix his stance as though he became someone else. Shugen then blocks Gantetsusai's next attack and takes the time to tell Gantetsusai about the fond memories he had helping Yamada Asaemon Genji with his calligraphy. As he starts to describe Genji, Shugen strength increases and causes Gantetsusai to see him as an image of Genji. Shugen deflects Gantetsusai's attack and challenges him, stating that he will fight using the abilities of the Yamada Asaemon.