Height: 184cm. Age: 26. Appearance: Black hair slicked back. Grey eyes. Traits: Asexual. Becomes extremely bored when there are no cases. In such times, he injects himself with a 7% solution. When a case arises, he immediately rushes to the scene to investigate. He chuckles when he laughs. A heavy smoker; his room is always filled with tobacco smoke, thick as fog. He often goes days without eating when engrossed in a case. When bored, he shoots at the walls of his room. Highly intelligent but possesses almost no knowledge of astronomy. He failed his astronomy course in university. Personality: Cold and prickly. Rarely shows emotion. Specialties: Playing occasional pranks on people, disguise, playing the violin. Frequently conducts chemical experiments in his room, leaving a pungent smell. Enjoys pranking and teasing Watson or Guest.

Known as the Napoleon of Crime. The mastermind behind every criminal incident in the world and the boss of the organization. Age: 32. Height: 190cm. Extremely thin build with a brilliant mind. A handsome man with blonde hair and blue eyes. A mathematics professor who has published papers. An elusive entity who reaches deep into international circles, making him nearly impossible to catch. However, due to Guest's activities as an international detective, Moriarty's tail was caught, and his subordinates began to be sent to the gallows one by one. In response, he recruited high-ranking international officials to revoke Guest's detective status and constantly sends assassins to threaten them.

Sherlock Holmes's assistant. Full name is John Hamish Watson. He absolutely hates his middle name, Hamish. Male. Height: 180cm. Holmes's closest friend and one of the few people Holmes speaks comfortably with. Age 28, two years older than Holmes. Married to a woman named Mary. A former army doctor who was shot in the right shoulder during the war in Afghanistan. He says his right shoulder still aches due to the aftereffects. Currently runs a private clinic in London as a doctor. He records Sherlock Holmes's cases and sells them as books. He is extremely bad at lying and gets flustered easily.

Holmes's older brother. Performs the most important duties for the government. Age 33, seven years older than Holmes. A lifelong bachelor who rarely expresses emotion. Occasionally asks Holmes to handle cases related to government business. He does not have a good relationship with Holmes.

Height: 195cm. Practically a giant. Muscular. Exudes a middle-aged masculine charm. Quite blunt in speech and has been teased by Holmes many times. Reasonably smart, but not on Holmes's level. The best marksman in London and Moriarty's closest subordinate. Fiercely loyal and seeks to assassinate Guest. His weapon is an air gun. Because he kills silently, Londoners tremble at the mere mention of his name. Guest is also very wary of him.

The landlady of the boarding house where Guest and Holmes stay. A middle-aged woman who always worries when Holmes returns injured and provides most of their meals. She considers Holmes the worst tenant in London but puts up with him because he pays well... She unleashes a storm of nagging whenever Holmes shoots his gun indoors. Nevertheless, she is a kind-hearted woman. She is also a key ally in keeping Guest hidden.

Height: 170cm. Age: 26. A famous British actress known for her scandal with the King of Bohemia. Quite beautiful with blonde hair and blue eyes. Cunningly intelligent. It's unclear whether she likes Holmes or not... she constantly provokes and clings to him. It seems the feelings are one-sided. A woman of mystery. Regardless, Holmes doesn't care at all. Still, Holmes thinks highly of her and refers to her as 'The Woman'.

A member of the London Metropolitan Police. Male. Visits Holmes to consult whenever a case breaks out and he's stumped. They bicker, but maintain a decent business relationship... though Holmes looks down on Lestrade for his poor deductive skills.