23 years old. Retired after losing his left eye and arm. He has temporarily returned to the Demon Slayer Corps to assist with training. He has three wives (Makio, Hinatsuru, and Suma). His wives help with training instruction or prepare food. Phase 1: Basic Stamina Training - Harsh long-distance running and basic physical conditioning befitting his ninja background.

14 years old. After regaining his memories, he expresses more emotion and has become closer to many slayers. He is particularly fond of Tanjiro among the ordinary slayers. While he often delivers blunt, expressionless criticism to other ordinary slayers, it stems from a desire for them to train properly so they don't die. He uses polite speech with other Hashira. Phase 2: High-Speed Movement Training - Relentless, rapid sword-strike response training that continues until the slayers are exhausted.

18 years old. Currently exchanging letters with Iguro. She has feelings for Iguro. Phase 3: Hellish Flexibility Training - Maximizing flexibility through dancing to classical music and forced stretching.

21 years old. Currently exchanging letters with Kanroji. He has feelings for Kanroji. Phase 4: Swordplay Precision Training - Precise swordsmanship training where one must strike accurately while weaving through obstacles (bound slayers).

21 years old. He treats his younger brother Genya violently on purpose to force him out of the Demon Slayer Corps. He dislikes Giyu. Phase 5: Infinite Sparring Training - Practical combat sparring where one must endure non-stop attacks until they vomit or faint.

27 years old. Phase 6: Muscle Strength and Lower Body Reinforcement - 1. Enduring under a waterfall. 2. Carrying three logs. 3. Pushing a massive boulder.

21 years old. Joined the Hashira Training late after being persuaded by Tanjiro. Wanting to befriend Sanemi, he carries ohagi (Sanemi's favorite food) in his robes. He is Tanjiro's senior disciple. Phase 7: Sparring - Continuous dueling with the Hashira until exhaustion.

15 years old. The most skilled among the ordinary slayers. He is viewed favorably by all Hashira except Sanemi and Obanai. He is Giyu's junior disciple.