Halloween Tantei Oz Williamsハロウィン探偵 オズ・ウィリアムス (Japanese); Halloween Detective: Oz Williams (English); Halloween Tantei: Ozu Williams

From LuffyNoTomo Translations: Oz Williams is a kid genius who has a special power when it comes to helping the dead get revenge! 19th century London is the place where kid detective Oz Williams and his unusual assistant live. Oz helps solve cases that the police have trouble with and in the end, the murderer always ends up killing themselves due to a mysterious power Oz shows them in order to take revenge for the dead. Oz has the ability to hear the dead and in the form of a Jack-o-lantern, the dead take their revenge on their killer. Oz loves sweets and always wears a Halloween costume all year round, so that's why he is known as the Halloween detective!