I remember very little about the manga except that it had the boy meets girl scenario. I think the girl was of the magical girlfriend type and was in dire need of clothing and a place to stay. The guy let her live at his home and let her borrow his mother's clothes (that's probably the only part I'm certain about). Since those mostly fit I think the girl was older than the guy (or at least had the physique of a woman), but I can be wrong. The mother (along with all other family members) was conveniently out on a buisness trip (or working abroad or something similar), but I think she actually showed up later on. I'm not 100% sure, but I think there was some romance between the guy and the girl.

Anyone knows the title of this manga?

BUMPing

The part I'm most certain about is that the guy tried to solve the girl's lack of of clothing problem by giving her his mother's clothes.