Zaki

Appearing to most as a samurai plush toy, Zaki is the spirit of a  young child that occupies Ruki's household. Ruki sees him as a little brother figure, though he affectionately calls her Mama despite her embarrassment.
As a zashiki warashi, Zaki is spiritually bound to a small area surrounding Ruki's home, leaving the rest of the outside world a total mystery to him. He's often waiting for Ruki to return whenever she leaves, but it doesn't mean his time home alone isn't interesting.
He stays on guard of any danger and fends off any threats (or what he believes are threats) when no one is around. Being just a child, he can't protect very well, but he does try!
He also plays with whatever friendly faces he sees passing by, and eavesdrops on Ruki's dad while he works.

Personality:
Zaki is super naive. He often doesn't know right from wrong, and anyone that looks or sounds or acts super scary he will immediately determine a threat and attempt to slay them. Unfortunately, most of Ruki's friends (often the yokai friends) happen to be not the friendliest in appearance and Zaki regularly attacks them out of impulse. It frustrates Ruki every time she has to reassure him that they aren't there to cause any trouble (on purpose)
He also has severe separation anxiety. Every time Ruki leaves, he gets scared of what could happen to her out there. He gets especially antsy when it's been a super long time since seeing her. Hearing her voice immediately perks him up, and he always welcomes her home with a loud shout: "Mama Ruki!"