Hm, I agree on this theme thing. I think the idea of a portfolio should be to show a good variety of what you can do. That's what they've had us doing at my college, anyway. I think anime artwork can certainly have its place, especially when it's your real area of interest, though you also want to specialize your portfolio for who is going to see it. You could switch out different pieces depending on who you're showing it too. At any rate, don't give up on anime artwork. Even if you can't use it for class right now, it's a great skill to keep developing (as well as a fun hobby ^_^), and hopefully you'll be able to use it in the future and in your career someday!