TV-Series
Description
Castor, who was born as Xing-lu Hausen, serves as one of the main bishops at the Barsburg Church in District 7. He is a young man in his early to mid-twenties, standing 180 centimeters tall, with reddish-brown hair and round glasses that give him a scholarly appearance. As a child, Castor was cold and emotionless due to being neglected by his father, which led him to spend most of his time making replica dolls, including one modeled after his mother. This hobby grew into a deep passion for creating life-sized puppets, which he controls using his rare manipulation-type Zaiphon.

His personality is defined by a blend of deep kindness and strict rationality. He is polite, welcoming, and always eager to help others, frequently visiting the district hospital to protect citizens and showing particular sympathy for children. He possesses a great deal of patience and remains optimistic even in dire situations, such as when he joked with a friend while bleeding from a serious injury. However, his rule-abiding nature can cause him to appear cold, as he is willing to prioritize duty over emotion, such as when he attempted to erase a character's memories to protect the secret of the Seven Ghosts despite knowing it would also erase precious final memories. He can be mischievous and enjoys pulling pranks, yet he also displays a merciless side in combat and is not above using physical discipline on irritating colleagues.

Born as the thirteenth head of the Hausen Family, his human life ended in tragedy. During a mission, he discovered and freed a mermaid named Razette, with whom he formed a close bond and dreamed of traveling the world as a puppet master and songstress. After the Raggs War, his family was forced to surrender his head as a condition for survival. His father attempted to sacrifice Razette by having her transform to look like Castor, but when his father moved to kill her, Castor shielded her and was fatally wounded. After his physical death, he was reborn as one of the Seven Ghosts, specifically the Ghost known as Fest. Upon awakening as a Ghost, he found that Razette had taken her own life in grief, so he used his new power to tie their souls together, allowing her to live again by sharing his life force.

Within the Barsburg Church, Castor works alongside his fellow bishops and forms key relationships that define his role in the story. He shares a particularly strong bond with Razette, whom he is very protective of, and the two remain together after his resurrection. His relationship with the bishop Frau is marked by constant bickering and name-calling, with Castor often acting as a voice of reason and disciplinarian who confiscates inappropriate items and scolds reckless behavior; despite their differences, there is a deep, unspoken brotherly respect between them. He is frequently seen with Labrador, trusting his premonitions and caring for his health, willing to risk his own life to protect him. While he does not get along well with Lance due to their conflicting personalities, Castor still acknowledges Lance's capabilities. He also takes on a mentorship role with the protagonist Teito Klein, helping him train for examinations and ensuring his safety, though his teaching methods are notoriously strenuous and earned him the nickname "smiling Spartan".

Throughout the story, Castor undergoes significant development. Once an emotionless child, he learned to smile through Razette's influence. As a Ghost, his past as Xing-lu is gradually revealed, adding depth to his calm demeanor. He suffers severe injuries in battle, losing an arm and an eye, which are later replaced with prosthetics. By the final chapter of the manga, he loses his Ghost powers and becomes an ordinary human once again.

Castor possesses several notable abilities. As the Ghost Fest, his primary power is the ability to tie together the souls of living beings, allowing him to resurrect the dead under specific conditions, such as when the soul still resides in the body and the death was not from natural causes. He uses this power with his ghost strings, which are sharp, barbed threads that extend from his palms, capable of restraining, stabbing, or slashing opponents. He can also use these strings to control his life-sized dolls in battle, making them indistinguishable from real people and using them as decoys or attackers. His Zaiphon is of the rare manipulation type, which allows him to move objects with his mind. Being a Ghost also grants him accelerated healing compared to ordinary humans.