YU-NO contains some tits and other softcore, but nothing hardcore I'm certain. It's supposed to be an amazingly good adventure game though, so it's still very sought after. The original PC98-version is supposed to contain explicit sex scenes while the Sega Saturn and Win95 versions didn't. Sega Saturn games have tons of tits, but I think there was never any real hardcore, even in the games that are rated "18", "X", "X-18" and whatnot.
Just thought it's funny because of the general frustration of players who have to play forever to have a girl undress in these games ^^