Muichiro Tokito, a Demon Slayer Corps member and younger twin of Yuichiro, grew up under a woodcutter father and mother until tragedy struck. Their mother died of bronchitis when the twins were ten; their father perished months later in a storm while gathering herbs. Left orphaned, Muichiro retained his father’s gentle nature, while Yuichiro hardened, condemning their parents’ altruism as folly. When Amane Ubuyashiki, wife of the Corps’ leader, sought to recruit the brothers at eleven, Yuichiro rebuffed her until a demon assaulted their home. Yuichiro shielded Muichiro during the attack, losing an arm before Muichiro slew the demon in a vengeful fury. Yuichiro succumbed to his injuries soon after, and Muichiro, gravely wounded, was rescued by Amane but lost all memory of his past. Adopting Yuichiro’s detached persona, he channeled his buried anguish into relentless training, ascending to Mist Hashira within two months.

Initially aloof and forgetful, Muichiro dismissed camaraderie, clashing with swordsmith Kotetsu over the Yoriichi Type Zero doll and mocking his skills. Yet Tanjiro Kamado’s rebuke of his callousness sparked introspection. When Kotetsu faced Gyokko’s demons, Muichiro defied his earlier indifference, saving him—a turning point echoing Tanjiro’s ideals. Trapped in Gyokko’s water prison during their battle, Muichiro’s submerged memories resurfaced, awakening his Demon Slayer Mark: a mist-patterned surge of power that neutralized poison and shattered Gyokko’s defenses. Reunited with his compassionate past and Yuichiro’s tenacity, he triumphed.

Mastering Mist Breathing techniques like Shifting Flow Slash and Obscuring Clouds, Muichiro wielded evasion and precision. Later, in the Infinity Castle clash against Kokushibo, he unlocked the Transparent World, predicting attacks through physiological cues, and scorched his blade crimson to cripple demonic healing. Despite losing limbs and suffering fatal wounds, he fought until Kokushibo fell, perishing shortly after with the Corps’ victory secured.

Post-memory restoration, Muichiro softened, thanking Tanjiro and prioritizing allies’ safety. He rekindled bonds through playful banter and perceptiveness, even detecting Obanai’s unspoken affection for Mitsuri. His journey—from a grief-stricken amnesiac to a warrior harmonizing reclaimed empathy with his brother’s iron will—cemented his legacy as a prodigy who transcended isolation to sacrifice everything for others.