Booty is booty
Yep, that booty was the only thing that made me interested in viewing this. Its strongest point is probably that is one well drawn butt. It almost doesn't seem to sync up well with the rest of the picture. I like how you included a bar code with your signature (or name) under it. This doesn't really look old at all. I imagine that a lot of submissions in the art portal would be older because it's the newest feature of its kind we have.
Is the girl supposed to be Nene? I didn't see how she would have tied in to Heavy Metal, but I guess it makes as much as sense as anything else. I like the vast amount of detail put into the strange building with all the instruments. The gun is probably the coolest part as it has so many neat parts to it. Oh, you included the date too.