The Fruit of Grisaia: Grisaia no Tokuten

Main cast features the protagonist plus several female characters who are romantically interested in them.

Features a character wearing no clothing or exposing intimate body parts.

Features sexual or romantic relations between characters who are related by blood.

Prominently features a character who generally retains a cold, blunt and cynical exterior, but once one gets to know them, they have a very warm and loving interior.