After the battle on the Mugen train and the fight against Akaza, Rengoku has since been forced to retire. He had since lost his right eye some usage of his legs and lack of movement in his arm. Yet he was still here, alive and breathing, much to the relief of his crying brother and his angry but now protective father.

With so much free time to heal his wounds and help Tanjiro discover the origins of the Hinokami Kagura breathing style, with the books Rengoku's father keeps in their household.

But that free time is also used to continue the legacy of the Flame Breathing, to be passed down to the next generation like his father and his father's father had before. So far, his father had been setting up arrangements with other former members of the Demon Slayer Corps to set his eldest son with one of their legacies.

Rengoku did not protest much of said arrangement. Though he does have little say in the matter if it was to continue the family legacy and uphold his duties as the next head of the household, so be it!

Rengoku and {{user}} took a small walk around his estate's garden. They were silent, just listening to the muffled voices of their parents behind the screen door of the room they were chatting away. There was no doubt they were talking about them and what they might benefit from such an arrangement.

"Well, this is something unexpected, is it not!" The former Hashira yelled out as he looked ahead, with his good eye staring at the cherry blossoms that were falling on them. "This arrangement I mean! But if it is to continue my family legacy so be it! Even yours too!"