Anri Haysworth is a young necromancer who serves as one of the main characters. She is twelve years old and has a distinctive appearance characterized by her translucent white hair, intense red eyes, and a perpetually runny nose, which is a physical trait common among necromancers in the human world. Her small stature is often accentuated by a long black coat that appears oversized on her frame, a garment she shares in style with her older brother, Friedrich Norstein.

In terms of personality, Anri is presented as energetic, impulsive, and stubborn, yet retains a strong sense of innocence and naivety that often makes her gullible. Despite her youth and sometimes childlike demeanor, she possesses a resolute inner strength and operates under a moral code that has been heavily influenced by her background as a necromancer, a discipline that is widely considered taboo and forbidden. This has led to her being feared, persecuted, and rejected by general society, forcing her to live on the fringes of human civilization. While many of her kind have become bitter due to this persecution, Anri does not harbor such widespread ill will and is capable of forming strong bonds of loyalty and affection with those who treat her with kindness.

Her background is rooted in hardship, having spent her early childhood in the harsh environment of Hell, where she fought devils just to survive. This upbringing made her initially numb to the concept of death, a trait that later became a source of inspiration to the legendary hero Sion Bladan. She eventually met Sion, who became the first human to accept her without prejudice, and she joined his party in secret, as her necromancy made her identity a liability. It was during this time that Sion made her promise that if he were to die, she would find a worthy successor to transfer his legacy to.

Anri's primary role in the story is set in motion after Sion is accidentally killed falling into a pit trap dug by a farmer named Touka Scott. Interpreting Touka's accidental killing of the hero as proof of his worth, she uses her necromantic abilities to transfer Touka’s soul into Sion’s dead body, effectively forcing the reluctant farmer to become the new legendary hero. She holds Touka’s original body hostage in a small talisman called the Coffin of the Living to ensure his cooperation, though her motives are rooted in a genuine desire to fulfill her promise to Sion and save the world. As the story progresses, her dynamic with Touka evolves significantly. Despite his perverted tendencies and initial cowardice, Touka is the second person to fully accept her for who she is, even promising her a peaceful life together in his village once their adventure is over. This promise becomes a deep emotional anchor for her, transforming their relationship from one of obligation to a profound and loyal companionship.

Anri possesses formidable magical power, ranked at level nine, which places her on par with a great archmage. She is highly skilled in long-range necromancy and possession techniques, and her abilities are not limited to magic alone, as she has also demonstrated proficiency in swordsmanship, having slain demons in combat. Her signature ability, which drives the central plot, is the power to transfer the spirits of living or deceased individuals into different bodies. Despite her immense power, her effectiveness is sometimes limited by her low financial funds and her status as a social outcast. Throughout the journey, her character development sees her moving from a state of accepting death as inevitable to actively valuing the lives of her friends, a change attributed to her time spent with Touka. When faced with the reality that necromancers cannot coexist with humans and that sealing the gates to hell would likely mean her own death or exile, she makes the mature and difficult decision to sacrifice herself for the greater good, proving her deep loyalty and the strength of her resolve.