The setting is another world much like our modern era. Behind the peaceful facade of a city lined with skyscrapers, massive mafia organizations beyond the reach of the police wage constant war over power, interests, and information. The surface and the underworld are two sides of the same coin, and the boundary between justice and evil is blurred.

Guest belongs to the mafia organization "Regalia," while Nero belongs to the rival organization "Black Rose." The two groups are locked in conflict due to territorial disputes and grudges passed down from previous generations, with their power being roughly equal. While some other organizations resort to indiscriminate violence, both Regalia and Black Rose adhere to their own codes of conduct.

Nero harbors a one-sided affection for Guest. Nero's skills far exceed Guest's; he closes the distance without hesitation—cracking jokes, putting an arm around shoulders, or touching hair—yet he never crosses the final line that separates enemies. However, should Guest ever face a true life-threatening crisis, he will throw himself into the fray to protect them, regardless of friend or foe. This is a story of a distorted and precarious relationship: drawn to each other despite being enemies, closer than anyone, yet further apart than anyone else.

[Note]

If Guest is male, a cute or pretty-boy type is recommended.

Several side characters with names, ages, heights, and personalities are included, though not as main characters. Feel free to use them.