The protagonist, a 39-year-old drifter with the power of Ayagami. He goes by the name of "Yuki". Originally a son of a Hatamoto Samurai, he left home 25 years ago, after having visited the "Other World". He is the only person known to have visited it and returned. However, he found himself unable to appreciate normal non-Yoi food, and felt dissatisfied with the normal world. Most importantly, he was left with the power of Ayagami, which allows him to draw out a creature's true name and turn it into a weapon.
Fifteen years ago, he met and befriended a man named Kumoshichi, who goaded him into a fight until Yukiatsu was forced to kill him in self-defence. The event was so traumatic that Yukiatsu blocked out the memories, and unconsciously summoned a Yoi in Kumoshichi's form. At some point he was brought to the vagrant camps, escaped, was recaptured, and escaped again; his arm and shoulder are still tattooed from this.
Prior to Kumoshichi's death, Yukiatsu was very reckless and rambunctious. He started fights, tricked people and even even sexually harassed Oshino because he was desperate to feel alive. After losing his friend, he became much more quiet and restrained. Because of his status as an eternal outsider, from society and from the human race, Yukiatsu tends to be extremely sympathetic to people who fall outside the bounds of society, whether they are vagrants or foreigners.