Yatori (夜烏) is the loyal servant of Akura-ou (now Kirihito) and previously worked for him. During that time, he was known as 'Furball'.
In the past when he was known as 'Furball', he was, as his name implied, resembles the shape of a ball and was covered in fur except where his face was. He had large almond-shaped eyes with spirally pupils and a small nose in between. His only garment was the tall hat on his head.
After consuming Sukeroku's body, Yatori now wears a big lion's-mane like headdress with a red monster's face in the middle. He has slanted green eyes with a the same ripple-like pattern. He wears a cheetah-patterned kimono with two bear-like paws on either his shoulder.
Yatori is foremost a sadistic, cruel demon. This In the past, when he was known as Furball, he seemed quiet and easily intimidated, especially by those larger and more powerful than him. Because he was bullied and abused for being considered ugly and weak, Furball developed a severe complex about his appearance. This came to a head when Kirakaburi abused and insulted him while they were on a mission. Kirakaburi was gravely injured and told Furball to get help while still insulting him. Furball decided to eat him and enjoyed the feeling of superiority and power he gained. He developed a power-hungry attitude. With his newfound strength, he possessed Sukeroku's body and finally gained the physical appearance he so desired. He even gave himself a new name- Yatori. Currently, he is very cheerful, talkative, playful, and easygoing, but can turn hateful and menacing in the blink of an eye. Yatori is endlessly loyal to Akura-oh, even as Akura-oh uses him and cares little for his wellbeing. Yatori is jealous of others such as Kikuchi and Tomoe for being closer to Akura-oh and is very opposed to the idea of Akura-Oh changing, especially due to the influence of Nanami whom he seeks to destroy at all costs. Yatori is sadistic and enjoys manipulating others using cheap tactics, but his tricks don't work on those who see through him or have strong wills such as Nanami. He seems to be gluttonous, as he is usually shown eating. Yatori values strength above all else and feels that those who are kind die first because they are weak. Despite this, he is shown to be a coward towards those more powerful than him, as shown when he reveals his true identity to Akura-oh as the other option was to lose his hand.
Yatori was previously known as 'Furball' and worked for Akura-ou after he killed his original master in a game of siege. He was constantly ignored and ridiculed for his appearance and weakness. His tolerance for it soon reached its peak when he was partnered with Kirakaburi.
When his accomplice Kirakaburi was severely weakened by Tomoe, Furball gorged on him. Due to this, his size and strength grew considerably. He soon finds out a human, namely Sukeroku, was watching him and makes him beg for his life, promising to never speak of what he witnessed. Furball relished this feeling of superiority.
Afterward, he aimed to get Akura-ou's recognition and protected him from human intruders by eating them. However, he was rejected again due to his appearance. Desperate to please him, he seeks out Sukeroku and eats him. He gains control over his body and afterward assumed the name 'Yatori'.
Yatori admires Akura-Ou for his strength and tenacity. He is extremely loyal to him. He states that the world under Master Akura-oh is his ideal world and his wish is to become Akura-ou's number one, a wish that is declined much to his dismay. Despite Akura-ou's attempt to kill him by taking him to the Yomi-no-kun under the assumption that Yatori would turn to dust Yatori claims that the only thing he couldn't forgive Akura-ou for would be if he changed.
Akura-ou does not recognise Yatori as his , largely due to his new appearance. Yatori does not reveal his past identity or the fact that he is aware that Kirhito is actually Akura-ou in human form until later in the series when his other option was to lose a hand.
Yatori first met Nanami on Kurama mountain where she defeated him with a Barrier Against Evil. He survived this and has held a grudge against her ever since. He becomes concerned throughout the series of Nanami's influence on Akura-ou and begins to fear she may change him. In Chapter 120 he suggests they kidnap Nanami to have Tomoe put out the hellfire engulfing his body, Akura-ou angrily refuses ordering him not to lay a hand on her. Yatori then asks if Akura-ou has feelings for Nanami, a question which Akura-ou dodges saying Yatori speaks too annoyingly.
Yatori detests Kikuichi, seeing him as competition for Akura-ou's approval. He frequently calls him names such as trash and unreliable. He is jealous of the more positive relationship Akura-ou has with Kikuichi and is always trying to undermine him.