I just remember that the main male character lives with his sister who is a model or something. I dont remember his name, but I'm quite sure he works as a photographer and has the habit of making himself up as a young beautiful girl for shooting.
His sister often embarasses him by loosening her clothes at home. The main character has a relationship with a little girl for a long time but they actually got laid in the last chapters of the manga.
I dont know if this is harem but this guy has several girlfriends himself.
I would be grateful for your help

Sounds like Yubisaki Milk Tea.

precisely ! thanks so much for help