Yoriichi Type Zero

Yoriichi Zeroshiki is a Battle Doll constructed by Kotetsu's ancestors during the Sengoku Era. According to Kotetsu's father, it was based off of an actual person, likely Yoriichi Tsugikuni.

Appearance
Yoriichi Zeroshiki's appearance largely resembles Yoriichi Tsugikuni, the person it was modelled after. It has six arms and hands that each hold a katana, due to the fact that two arms weren't enough to completely replicate Tsugikuni's movements. It is also shown to be heavily damaged, with half of its face and one of its arms missing.

Swordsmith Village Arc
Tanjirou trained with it while he was at the village

Abilities and Powers
Yoriichi Zeroshiki has 108 different movements based off of the person it was modelled after. Its power surpasses most humans, which is why it is used as a training dummy for Demon Slayers.