Byakuya is a supporting character in the Kakuriyo no Yadomeshi series, recognizable as a white hakutaku, a rare and wise type of ayakashi spirit. He has deep blue eyes, a long white mane that often covers part of his face, and wears a formal white kimono. A diamond-shaped monocle over his left eye adds to his image as a meticulous and sharp-minded individual. His very presence carries an air of strictness and authority, which aligns perfectly with his position as the chief of the accounting office at Tenjin-ya, the grand inn where much of the story takes place.

Personality-wise, Byakuya is defined by his cool pragmatism and strict adherence to rules. His personal doctrine is to cut away things with no potential and invest only in sure opportunities. He initially presents as unfriendly and keeps his distance from other employees, preferring to focus on his work. However, this stern exterior hides a softer side, particularly revealed when protagonist Aoi discovers him secretly playing with tube kittens in the forest. He is flustered by this discovery and works hard to maintain his reputation as a formidable chief of accounting, despite his hidden fondness for these small creatures.

Byakuya’s background reveals a long and complex history. He originally worked as a high-ranking official at the imperial palace, a position that commanded respect even from the most powerful figures in the spirit world. A pivotal event in his past was his marriage to a human woman named Shizuna. Her death plunged him into a period of deep despair. He was eventually pulled from this state by the Golden Boy, who introduced him to a young Odanna, the future master of Tenjin-ya. Recognizing Odanna as his true lord, Byakuya found new purpose and has served as a loyal and trusted confidant for many years.

In the story, Byakuya plays a crucial role as the arbiter of Tenjin-ya’s finances. Initially, this puts him at odds with Aoi, as he views her newly opened restaurant, Moonflower, as an unprofitable risk and suggests it should be closed. His antagonism is further fueled by a long-standing grudge against Aoi’s deceased grandfather, Shiro Tsubaki, who accumulated a massive debt at the inn through unpaid bills and constant trouble-making. Over time, Byakuya’s opinion of Aoi shifts. He comes to respect her determination, and following the discovery of his affection for the tube kittens, their relationship evolves into a brotherly bond. He becomes one of her most valuable and trusted allies.

Byakuya’s key relationships are central to his character. His respect for the master innkeeper, Odanna, is absolute, and he is entrusted with running the entire inn in Odanna’s absence. His dynamic with Aoi transforms from cold professional disdain to genuine care. Notably, the thunder beast Raiju displays an inexplicable and hysterical fear of Byakuya, a reaction that hints at a shared past and establishes Byakuya as one of the few characters who can stand up to him without fear of reprisal.

Throughout the series, Byakuya leaves his desk to become an active participant in the main conflict. When Odanna goes missing, Byakuya takes charge of the effort to rescue him, becoming a close ally to Aoi during the perilous quest. In the second season, he plays a key role in confronting political powers to ease the pressure on Tenjin-ya and is later seen confronting the ayakashi emperor directly. His development shows a movement from a cold, pragmatic accountant to a loyal protector willing to take great risks for those he cares about.

As a hakutaku, Byakuya possesses potent supernatural abilities. He is said to have nine spiritual eyes that allow him to perceive almost anything, enhancing his analytical skills. He can perform high-level "spiriting away" techniques and a "body binding" spell that can restrain enemies with invisible bonds. He also has the power to heal others with magic. His abilities in battle and information-gathering make him a formidable force, as seen when he confronts Raiju and other dangerous foes to protect his allies.