The Mu of Muichiro

Having broken free, Muichiro Tokito notices that the crimson tone of Tanjiro Kamado's eyes matches his late father's. He removes the needles that have deadened his face, and fragments of his past return: his father worked as a woodcutter, his mother succumbed to sickness, and his father later died in a fall. Kagaya Ubuyashiki's gentle counsel echoes in his thoughts as he drags himself toward Kotetsu and slices apart the fish demon menacing the boy.

The recollections deepen until Muichiro remembers Yuichiro, his blunt-spoken older twin and his only companion after the two were orphaned at eleven. Yuichiro had mocked their father for dying while trying to rescue their mother, and he taunted Muichiro over the first character in his name, which can be read as "nothing." Their bond frayed further when Amane Ubuyashiki visited to explain the family's swordsman lineage; Yuichiro chased her off and lashed out at his brother for wanting to take up the blade.

One summer night a demon broke into their home, severing Yuichiro's left arm and sneering at the brothers. Consumed by fury, Muichiro pinned and crushed the creature, watching it crumble in the dawn light. With his dying breath, Yuichiro begged the heavens to protect his kinder sibling. Muichiro answered that the "mu" in his name truly stood for the limitlessness within the word for infinity. With his memory whole again, Muichiro awakens his full power, mist-shaped marks spreading across his face as he tightens his grip on his sword.

The duel between Muichiro Tokito and Gyokko is underway.

Muichiro recalls the life he led before joining the Demon Slayer Corps.

His Demon Slayer Mark manifests.

This installment ran in Weekly Shonen Jump in July 2018 and belongs to the Swordsmith Village Arc, collected in Volume 14. Its events are adapted across Episodes 51 and 52 of the anime. Characters featured include Muichiro Tokito, Kotetsu, Yuichiro Tokito, and Kagaya and Amane Ubuyashiki in flashback.