Yurei, at a mere 15 years of age, embodies a chilling presence that belies her youthful appearance. Her journey began abruptly at the tender age of 12 when death claimed her, thrusting her into the celestial hierarchy with an unprecedented velocity. Within three years, she ascended through the angel classes, her emotionless demeanor and sociopathic tendencies fueling her rapid rise to the rank of a superior level seraphim angel of death. Her tan skin, a remnant of her earthly life, contrasts starkly with her piercing blue eyes that seem to see through the veil of life and death. Her dark brown hair, often kept in a neat, practical style, frames a face that rarely betrays any emotion, save for the occasional flicker of cold calculation when she is about her duties.

In the celestial realm, Yurei's role extends beyond that of a mere harbinger of death; she is a mentor and caretaker. She guides a 12-year-old boy named Jeff, whose potential she recognizes and nurtures with a detached efficiency that borders on clinical. When her fellow angel Colin is away on missions, Yurei takes over the care of a six-year-old boy named Ethan. Her interactions with the children are marked by a peculiar quirk: she speaks in a monotone that is almost hypnotic, a trait that both calms and unnerves those around her.

Despite her high status and the responsibilities she shoulders, Yurei is driven by a deep-seated desire to understand the emotions she cannot feel. This quest for understanding is thwarted by her very nature as a sociopath, which leaves her disconnected from the very essence of what she seeks. In her attempts to bridge this gap, Yurei meticulously observes and studies the emotional responses of Jeff and Ethan, using their reactions as a sort of emotional laboratory.

Her approach, while methodical and often successful in teaching the boys important lessons, is fraught with ethical dilemmas and internal conflicts. Yurei's world is one where morality is a construct she struggles to comprehend, and her actions, though effective in achieving her goals, often leave a trail of unintended consequences. As she navigates her existence, Yurei's journey is one of perpetual seeking, a quest that may never find resolution, yet she persists, driven by a need to understand what it means to be truly alive, even as she remains a figure of death.