Demon Slayer: Kimetsu no Yaiba Episode 25: Tsuguko, Kanao Tsuyuri

Tanjiro enlists the help of Naho, Kiyo, and Sumi to flog him whenever he stops using Total Concentration Breathing, even while sleeping, and they eagerly agree, beating him repeatedly as he snores despite the pain.

The swordsmith Haganezuka angrily delivers Tanjiro's new sword while threatening him with a knife for breaking the previous one; meanwhile, Inosuke's swordsmith Kanamori presents his blades, which turn bluish-grey, but Inosuke unsatisfiedly files teeth-like grooves into them with a rock, enraging both smiths.

The three girls confirm Tanjiro's improved breathing, and the next day he finally beats Kanao at tag and the tea-spilling reflex game by knocking over her cup first.

Zenitsu and Inosuke, feeling pressured, begin their own training after Shinobu motivates Inosuke by calling him weak for lacking constant breathing and Zenitsu by appealing to his interest in girls.

A flashback reveals Kanao's harsh childhood as an abused, mute orphan slave forced to obey orders without question; she snaps mentally amid her suffering until Shinobu and her late sister Kanae rescue and adopt her as a tsuguko, giving her a coin to flip for decisions since she cannot make her own.

Shinobu examines the fully recovered Tanjiro, confirms his readiness for missions, and explains she only knows Breath of Flames, suggesting the Flame Hashira Rengoku might know about the Dance of the Fire God or Breath of the Sun, though Rengoku is currently on a mission involving mysterious train deaths.

That night, Tanjiro visits the sleeping Nezuko in her box, expresses worry, promises to join missions soon with his friends, and vows to gather more demon blood for Lady Tamayo's research.

Far away, an unseen demon terrorizes passengers on a train.