Train

With their fun having to take a pause, Banjiro, Nezuko, Inosuke, Zenitsu, and Rengoku board the train. Inosuke and Nezuko try to fuck Banjiro as Zenitsu shamefully hardens, but Banjiro stops them, using Rengoku to remind them of their situation.

Now, with resolve and clearing their mind of sexual desire, Banjiro and his team envelop themselves in the atmosphere.

They are still on alert, but they are calm, and so when the train turns out to be a lower Kizuki, it is Banjiro and Rengoku that launch into action, leaving the others to follow behind. Together, they push towards the front, ready to kill the Demon, only for Akaza to come out far earlier than Banjiro had planned. Once emerged, the group tried to fight off Akaza, but the Train Demon offered a surprisingly helpful hand in wounding the team, forcing Rengoku to make the same heroic sacrifice that took him before.

In this situation, Banjiro tried to remain strong, but he cursed himself for not being able to save Rengoku, stopping the blood as best he could while looking at Nezuko, realising there was a chance as he had her spill his blood into his wounds and mouth. Banjiro knew Rengoku refused Akaza's offer to become a Demon, but he hoped Rengoku would forgive Banjiro as Rengoku's injuries healed. Rengoku was still impossibly injured, but with a night, his life-threatening injuries began to knit themselves back together, giving Banjiro a sense of relief as he looked at Rengoku, only to realise the transformation wasn't stopping, leading Rengoku to turn into a futanari.

His lips grew plumper, his hair grew out, and his frame became smaller, yet thicker. As she awoke, she was confused, but looking at her body and Nezuko's blood, Rengoku put two and two together, contemplating his situation before desire overcame her and she masturbated furiously, cumming all over Nezuko as she opened her pussy, pleading for release as Banjiro came up to the task, revealing his massive dick to her pussy as they fucked in the night, adding Nezuko to the pile after Rengoku pleaded for more of this, becoming Banjiro's woman in exchange for using her dick on his fine bitches.

With Rengoku becoming his woman, Banjiro was fine with her using his harem, causing a lightbulb to pop in his head as he looked to Zenitsu, asking if he wanted to join their fun. When Zenitsu learned of Banjiro's plan, he hesitated for a moment, but then he agreed, becoming another futanari, although with a significantly smaller dick than even the futanari Rengoku.

Still, he was just happy to be included and finally love his Nezuko-chan, leading to the group returning to the Demon Slayer Corps to add Obanai, who became a full woman, fully joining Mitsuri in the pleasures of the female flesh.