Masamune Urachi is the director of the Administration Bureau, the organization that monitors and manages the special abilities of the residents of Sakurada. He is a tall, handsome young man with dark blue hair and dark blue eyes, and he is almost always seen wearing a suit. His ability allows him to rewind the time of objects and humans he makes physical contact with, resetting them to an earlier state. The maximum range of this rewind is generally described as up to five years, though some estimates suggest his practical limit is closer to two years, and the restored state can last for up to three years before the effect naturally wears off.

Urachi uses his power strategically, and one of its most distinctive applications is the ability to erase his own memory. By regularly rewinding his own mind, he ensures that he cannot be influenced or predicted by those who might try to read or manipulate his thoughts. This makes him immune to Sumire Souma's power, which relies on understanding a person's past experiences. His personality is calm, calculating, and detached; he approaches problems with a bureaucratic and often ruthless pragmatism, believing that the Bureau's oversight is necessary for the town's stability.

In the story, Urachi serves as a primary antagonist and authority figure. He is the highest-ranking member of the Bureau that the main characters, Kei Asai and Misora Haruki, must contend with. His motivations center on maintaining control over Sakurada's ability users and preventing any disruption to the town's established order. He views powerful abilities as potential threats that require containment rather than opportunities for progress.

His key relationships are largely adversarial. He opposes Kei and Misora's efforts to use their abilities outside the Bureau's framework, and he has a tense, manipulative dynamic with Sumire Souma, whose own power cannot touch him due to his memory erasure. Over the course of the series, Urachi's role develops as the Bureau's true plans and the limits of his ability are revealed. His unwavering dedication to the Bureau's mission and his willingness to sacrifice personal connections make him a formidable obstacle, but also a character whose logic and methods are debated by those around him. His notable abilities, aside from time rewind and memory erasure, include the authority and resources of the Bureau, which he wields to surveil and control the town's ability users.