Bishoujo Comic Lolicon Angel ~ Taste of Honey ~ (1985)

Three young girls try to identify a thief who stole money from one of them. There are three suspects and each girl investigates them separately. The suspects are: a girl from their class with a secret connection to her teacher, a young boy from their class who's in love with the girl that investigates him, and an old man from school who mistakes the girl that investigates him as his daughter.