Gas-tou Norainu Tanteidan

Overview

Late 19th century, London. Rui, a boy living as a vagrant in the back alleys, encounters Sherlock Holmes, a detective, after becoming entangled in a murder case. Despite his resentment of Holmes's indifference to the lower classes, Rui decides to work under him as a “hound” to save the street children caught in the swirling crimes and conspiracies of London—the “demonic city.” Thus begins a mystery epic set in the underground world of street children! (Source: MANGA MILLION)

Source: AniList