So, in the game Record of Agarest War Zero, there is a trophy/achievement/milestone dubbed "hikikomori." Do I need to explain more? If anything, I write for this kind of site just so I don't have to. Well, no, that's unfair. I'll link to our database on the subject.
Other than that, the game itself seems like one of those terribly odd games we'll never see stateside. Sequel to Record of Agarest, the RPGs have featured a "Soul Breeding" system. Basically, you charm various heroines, and well... umm... create more powerful offspring, or umm... something. I doubt its actually an H-game, but the cat girl and bananas are telling me a different story.