Yatsu is a minor character of Kimetsu no Yaiba. He is a civilian that [Muzan Kibutsuji](https://anilist.co/character/129132/Muzan-Kibutsuji) bumped into at an alleyway in Asakusa.

It is the Taisho Period in Japan. Tanjiro, a kindhearted boy who sells charcoal for a living, finds his family slaughtered by a demon. To make matters worse, his younger sister Nezuko, the sole survivor, has been transformed into a demon herself. Though devastated by this grim reality, Tanjiro resolves to become a “demon slayer” so that he can turn his sister back into a human, and kill the demon that massacred his family. 
 
(Source: Crunchyroll)

The setting is Taisho era Japan. Tanjirou is a kindhearted young boy who lived peacefully with his family as a coal seller. Their normal life changes completely when his family is slaughtered by demons. The only other survivor, Tanjirou's younger sister Nezuko, has become a ferocious demon. In order to return Nezuko to normal and get revenge on the demon that killed their family, the two of them depart on a journey. From a young talent, an adventure tale of blood and swords begins!
 
(Source: Shonen Jump)
 
Notes: 
- Includes two extra chapters. 
- Nominated to the 24th and 25th Annual Tezuka Osamu Cultural Prize.