Gantz - It is an anime not intended for child viewing. Asusual it is a Japanese manga series. It is a story of two high school student hit by a subway train in an attempt to save the life of a drunk homeless man who had fallen onto the tracks. This is only the beginning.
This anime have nudity, sex and full of cursing. To me it is also a story of a high school student living in an apartment alone with a fantasy that will soon become reality in a very different way.