While watching Muichiro Tokito train against the mechanical doll, Tanjiro looks at the doll's face and ponders the idea that he has seen it before. He asks the young boy why the doll had six arms, in which he is told that as it was modeled after a real swordsman, the doll's six arms were necessary to imitate his movements. Tanjiro tries to push for more information, but the boy apologizes and states he didn't know much else, besides that it originated in the Sengoku period. Surprised, Tanjiro notes how that must mean Yoriichi Type Zero is over three hundred years old and even so, it still hadn't been destroyed. The boy replies that his ancestors were able to construct the doll at a level that couldn't be accomplished again at the present time—hence its durability—and he wouldn't be able to fix it himself especially without the aid of his late father, given that he doesn't possess the knowledge or skills to do so. Hearing this, Tanjiro understands the reasoning behind his resolve to not hand over the key to someone that could potentially break the doll.
The two observe Muichiro for a while longer and Tanjiro admires the Hashira's uncanny degree of skill, despite being of similar age. Muichiro's Kasugai Crows chips in and loudly praises her master's abilities, referring to him as a descendant of the Sun Breathing users and a genius completely different from Tanjiro. Amazed at his bloodline heritage, Tanjiro curiously inquires why Muichiro wasn't able to use the Sun Breathing, which receives him an angry assault by the crow. While he is being attacked by her, Tanjiro suddenly remembers the dream he had and how the swordsman he saw had a face that matched that of the doll's. Hearing his words, the crow stops and grumpily questions the logic behind his words, given how the swordsman was from so long ago. The young boy pitches in, proposing that perhaps it was a memory that was passed on, providing the example of a swordsmith "inheriting" memories of their swords and skills from ancestors, suggesting it may be similar to what Tanjiro was experiencing. The crow thinks of this idea as nonsense but is cut off as Tanjiro introduces himself to the boy, and the boy introduces himself as Kotetsu.
Suddenly, the group hears a sound and witness Muichiro destroying parts of the doll, with pieces of its armor flying away. Devastated at the sight, Kotetsu runs away and hides in a tree, crying over the broken doll. Tanjiro finds him and attempts to motivate him by saying he'll eventually be able to improve and fix it, in which Kotetsu replies that he is too pathetic to do so. Tanjiro climbs up the tree and flicks Kotetsu as a method of snapping him back into reality, exclaiming how he had to make the effort and develop the skills so that even if he wasn't able to fix Yoriichi Type Zero, the generations after him would. Tanjiro compares his struggle with Kotetsu's, affirming that even if he dies before he is able to accomplish his goals, someone else will eventually be able to do so in his place so long as the framework is set. Cheered up, Kotetsu and Tanjiro conclude to determinedly work hard together.
While they chat during a walk through the forest, they encounter Muichiro again who expresses that the training was helpful; however, his sword broke, so he will be taking one of the doll's swords. He tosses the broken sword indifferently to Tanjiro, asking him to discard it. Although confused by the swordsman's attitude, Tanjiro notes he lacked a malicious aura and likely wasn't acting rudely on purpose.
A storm brews overhead as Tanjiro rushes to Kotetsu, who appears aloof while staring at the broken doll in the rain. Tanjiro suggests they check if it can still move, which is met by approval from the boy. As they pick it up, it remains stagnant for a few moments before suddenly shifting into a stance, much to Tanjiro's excitement. Kotetsu then fiercely orders him to train with the doll and become stronger than Muichiro with his aid, surprising him.
Characters in Order of Appearance
- Muichiro fights against and breaks part of Yoriichi Type Zero.
- Kotetsu orders Tanjiro to train against the doll.