I think this seriously depends on your opinion of what "adult" is. Japanese games, manga, anime, etc had a lot more casual T&A in them 20 years ago than they do now. Stuff like Aim for the Top!: Gunbuster 2, and Starling Odyssey 2 have risque stuff in them, but certainly aren't "adult" by any means. I think the first Yuna game even has a nipple in it (a instant "M" rating in the US) but the game, lets face it, is pretty innocent.