Yoriichi
Tsugikuni

Yoriichi is a legend the show is still unwrapping. A Sengoku-era swordsman who wore hanafuda earrings identical to Tanjiro's, he was the wielder of Sun Breathing, the first Breathing Style, from which every school in the Corps descends. Through episode 63 he has never appeared in the present day, only in fragments: Tanjiro's inherited dreams of an ancestor named Sumiyoshi quietly hosting a somber guest, and glimpses of a swordsman whose stillness reads as sadness.

The Swordsmith Village arc made the legend physical. The Yoriichi Type Zero is a mechanical training doll built three hundred years ago with six arms, because, the swordsmith boy Kotetsu explains, six arms were needed to approximate the real man's movements. Muichiro sharpened himself against it; inside it, Tanjiro found a rusted blade from another age. Every new fact lands the same way: whatever Yoriichi was, the story's present is still living in his shadow, and Tanjiro's Hinokami Kagura is somehow his inheritance.