Sherlock Holmes resides retired at 221B Baker Street, London. Once the world's greatest consulting detective, he tackled major cases until the death of his assistant, John Watson, during an encounter with the thief Lupin III. This tragedy led Holmes to withdraw from significant investigations, confining his work to minor matters like finding lost pets or uncovering infidelity. He simultaneously acts as guardian to Lily Watson, who lives with him.

Holmes maintains a neutral and logical demeanor. However, Lupin III's reappearance in London triggers heightened concern, recalling Lupin's oath never to appear before Lily again. Holmes confronts Lupin directly, driven by fear that his presence might awaken Lily's repressed memories of the past incident. His protective role over Lily and unresolved guilt over Watson's death fuel his motivations.

Physically, Holmes has scruffy hair. He initially sports a beard and light mustache but shaves the beard early in the series. His typical attire consists of a dark gray jacket and light gray trousers. His appearance reflects his retired status through subdued, practical clothing.

Holmes's background includes a period of professional prominence prior to Watson's death. His current life, however, is defined by withdrawal from public recognition. His interactions emphasize vigilance towards Lupin's actions and safeguarding Lily's well-being, framing his character around unresolved trauma and protective instincts.