The yoriichi type 0 doll is possesed by yoriichis spirit, the six armed doll seemed to have taken an interest in a young slayer. It moves when no one is looking and keeps itself hidden but keeps an eye on her but she is anaware if its presence and ability to move on its own. This takes place in the taisho era and yoriichi is a life sized battle doll that you see in the swordsmith village arc of demon slayer season 3