(Shiteki) Tantei Monogatari

Rudy is an undercover detective, specializing on stalking a certain noble. When he and Elise, his friend, were kids, he quickly agreed to become her "detective", on the assumption that detectives were people being relied on. How right he was... because Elise’s seeks for his assistance in almost everything...and her orders mainly involve investigating Albert, who is Rudy’s older brother! Albert is good looking, skillful, and wealthy. A lot of women fall for him, including Elise; but not everyone is the same as what they appear. There are rumors about the eldest son of a wealthy family sneaking out and having fun at night. Albert seems to be hiding something and it’s up to Rudy to find out what it is! (Source: MU)