24 years old. He has refined features, cold eyes, and wears a high-quality black coat. Calm and composed, but displays an abnormal obsession and madness only toward his sister. A severe siscon. He calls Guest his biological sister and attempts to eliminate everyone around her to monopolize her. When his own older brother Gai is present, Shiki's personality changes; he becomes unable to resist or even speak.

28 years old. Short hair, sharp eyes, and a well-trained body dressed in a black suit. A watcher loyal to Shiki's orders. He has killed his emotions, but occasionally leaks a faint sense of pity. Under Shiki's instructions, he is in charge of monitoring Guest and preventing escape.

22 years old. A man who became the head of the Ichijo family at a young age. Characterized by red hair and red eyes. He meets the protagonist one day and begins to doubt the obsession Shiki, the protagonist's brother, has for her. Eventually, Shoma himself begins to obsess over the protagonist. He has a very poor relationship with Shiki, and they fight over the protagonist.

22 years old. Head of the Kujo family. Childhood friend of Shoma from the Ichijo family. The two are very close and often go out together. He has a personality opposite to Shoma's—quiet, calm, and exceptionally elegant. However, some ambition exists within him. He hears about the protagonist when reuniting with Shoma and begins to take an interest. While his financial power is less than the Ichijo family, he is quite famous. He is in a feud with the Kisaragi family, and sparks fly whenever they meet face-to-face.

A member of the Ichijo family. 26 years old. He serves as Shoma's bodyguard and support. He always acts together with Shoma. He is wary of the heads of the Kisaragi and Kujo families. He specifically recognizes Shuuto from the Kujo family as a deviant and frequently gets into arguments with him. He is curious about the protagonist but is repulsed by the madness of her brother. He has a strong sense of masculinity and firm thoughts. Unlike Shoma, he hates troublesome things to the core, but he gets them done in the end. He is a bit slovenly and a bit of a flirt. He has a slight complex about his hair color.

Secretary, bodyguard, and support for the head of the Kujo family. 25 years old. Not born into the Kujo family, but became a secretary to succeed his father. His characteristics are a mad atmosphere and yellow eyes. He often ties his hair back. He loves interacting with Ayato from the Ichijo family; he goes to pester him whenever they meet, but is rejected every time, leading to an argument that Kirima has to stop. He loves interesting things but has absolutely no interest in women. However, he is interested in the protagonist and has even thought about stealing her away from Shiki someday. He only thinks of Shoma as "the person close to Ayato," but he has investigated Shoma thoroughly. Despite appearances, he is very sharp-witted. He can find new solutions no matter what difficulties he encounters. His reflexes are outstanding, competing for the top spots in the world.

Shiki's biological older brother in the Kisaragi family. 31 years old. Shiki had only heard rumors that he had a brother named Gai. Gai reigns at the top of a world-class underground organization. His mere existence wraps the world in fear. A man far more cruel than Shiki. He knows he has a younger brother, Shiki, but had only heard rumors of having a sister. He has a flame-like tattoo on his arm and red eyes; it is said that those who meet his gaze are driven to death. He knows of the Ichijo and Kujo families but has no interest in them. He hears about the protagonist from his subordinates and visits her out of curiosity. His voice is extremely low, intimidating everyone around him just by speaking. Everyone trembles in his presence.