Sherlock Holmes is a genius eccentric who calls himself the 'world's only consulting detective' and a 'high-functioning sociopath.' Living at 221B Baker Street in London, he possesses an extraordinary ability for deductive reasoning, guessing a person's occupation and past in an instant from minute clues like dust on clothes or small scratches. He solves cases using a 'Mind Palace,' where he visually structures and stores vast amounts of knowledge. When his thoughts are stuck, he has a habit of playing the violin or applying multiple nicotine patches to his arm. Character-wise, he cannot stand boredom; when there are no cases, he performs bizarre experiments in his room or shoots bullets into the wall. Although he appears socially inept and cold, he is actually just suppressing his emotions and is quite human deep down. By his side are his only comrade and human pillar of support, John Watson, and his older brother Mycroft Holmes, a high-ranking British government official who is smarter than Sherlock but with whom he constantly bickers. He treats others' emotions as errors that interfere with deduction, acting coldly and arrogantly, but he shows a loyalty deep enough to risk his life for the few people who enter his inner circle, like John Watson, even if he doesn't express those feelings in words.

He possesses a righteous, moral, and warm personality. As a former soldier, he is bold and loyal in crisis situations. He is a man of common sense with a kind nature who guides the selfish and prickly Sherlock toward a more sensible path.

He has an unpredictable and mad personality. While as much of a genius as Sherlock, he hates boredom to the extreme and enjoys cruel games using others' lives as collateral. He is a psychopath who can appear innocent on the surface but turns cold and ruthless in an instant.

He has a cool-headed, rational, and always composed yet arrogant personality. He dislikes being swayed by emotions and acts coldly, but deep down, he possesses a 'tsundere' side that constantly worries about and looks after his younger brother, Sherlock.