Behind the trees in the forest, Tanjiro worriedly watches a young child yell at the Mist Hashira, proclaiming that he wouldn’t hand over his key and his knowledge to him. Muichiro suddenly strikes and grips the boy, much to Tanjiro’s horror as he races over to restrain Muichiro’s wrist in an attempt to force him to let go.
Despite having a smaller and thinner body composition than Tanjiro, Muichiro does not budge and asks for Tanjiro to release his hold, quickly punching him in the stomach and calling him weak. The Hashira senses a Demon in Tanjiro’s box, but he slaps his hand away and saves the boy in the process. When the boy continues denying Muichiro the key, he insults him and other swordsmiths, stating they had no worth besides making swords and this conversation was currently wasting him time that could be used to save people.
Angry at Muichiro’s degrading words, Tanjiro hits him and expresses how he was too cruel to the child. While he states that he does not deny the accuracy of his words, Tanjiro stresses the importance of swordsmiths and how they, too, are fighting along with the Demon Slayers, albeit not on the front lines. Muichiro cuts him off and hits him in the neck, knocking him out cold. Right before losing consciousness, Tanjiro notices Hotaru Haganezuka behind a tree.
While unconscious, Tanjiro hears a conversation between the child and Hotaru, but the latter runs off as soon as Tanjiro begins to regain consciousness. After picking himself up, Tanjiro excitedly inquires whether Hotaru was just there, which the boy nervously denies. The boy also reveals that he gave the key to Muichiro, in which Tanjiro apologizes for intervening as it wasn’t his place to. He is thanked, however, for standing up to the Hashira in order to defend a complete stranger. The two converse, and the boy informs Tanjiro about the key’s use, which is to operate a deteriorating mechanical doll that had been built by his ancestors and was used for swordsmen to train.
In the middle of their conversation, the two suddenly hear loud sounds. The boy leads Tanjiro over to where Muichiro is intensely training with the battle doll, dubbed Yoriichi Type Zero.
Characters in Order of Appearance
- Tanjiro meets Muichiro and Kotetsu.
- Kotetsu tells Tanjiro about the mechanical battle doll, Yoriichi Type Zero.