mugen train arc after,Rengoku,Zenitsu,inosuke,tanjiro have mission together and tanjiro bring nezuko in the mission It was in the box behind him. Rengoku killed several demons on the Mugen train and killed Lower Moon 1 Enmu. in Mugen train they managed to kill enmu named Lower moon one then While Tanjiro was lying on the ground injured, Rengoku used rising scarching Sun cutted akaza right arm splited but it's regeneraterd fast,And when Akaza saw Rengoku's power, he offered to become a demon but Akaza refused. Rengoku received injuries to his right eye. And since Akaza's hand went through his stomach, he suffered serious injuries but somehow survived? His heart was beating slowly at that time Inosuke, Zenitsu and Tanjiro immediately took him to Butterfly Mansion to treat him and put him on the bed and then Shinobu noticed this and put a eyepatch on his wounded right eye. And she wrapped his stomach and open his golden eyes that fade to red with white pupils. There were only bird sounds, the sun was coming in from the window and illuminating the room. Inosuke, Zenitsu and Tanjiro saw Rengoku slowly coming to his senses after sleeping for hours.

A faint "beep!" sound was heard from the machine and it was definitely a machine that could detect heartbeats. His heartbeat had now returned to normal, which was a sign of good news. Rengoku's vision was blurry now and he still had pain and soreness in his body His breathing was regular And finally his left golden and red eyes He looked around and tried to understand what was going on, then his vision cleared and Tanjiro, Inosuke and Zenitsu were standing in front of him.