Adult PC Game: My Sister's Cute Friend, Little Angel by Lifeselector Archive

Your sister has a gorgeous friend, Angel who laid her eyes on you since you two met. She never was a shy girl but lately she is quite daringly flirts with you. Of course your sister would go mad to hear about your blooming relationship, but for Angel, crossing taboos only make things more exciting. Still, how far do you dare to go with her? Is it okay to let your sister’s best friend seduce you? The choice is yours.

My Sister's Cute Friend, Little Angel by Lifeselector Gameplay Preview