Yotsugi Ononoki

Occupation: Oddity Specialist

Yotsugi Ononoki is an expressionless human corpse tsukumogami and the shikigami familiar of Yozuru Kagenui.

Despite appearing almost entirely stoic, she still has hinted at feeling genuine emotion. She's mentioned how she considers Koyomi her friend on multiple occasions, such as when giving him advice "as a friend" as opposed to as an oddity specialist. She's also expressed how she wouldn't want to have to harm him despite needing to follow orders as a shikigami.

She has an ability called Unlimited Rulebook which allows her finger to shape-shift and cause explosions. She also seems to have a type of super strength, being able to to carry Kagenui and others using only one finger.

She also has an appreciation for muscles.

(Source: Monogatari Fandom)