Leaving and coming back

Hey, I was curious on leaving and returning Japan with a student visa. I noticed, the last time I went to study abroad in Japan, when we left to go home, they took my gaijin card away at the airport even though that card was good for at least a year (we studied for 3 months). If I want to visit family and friends in America this time (I'll study for a year) will they still take it away? Will I get it back?

You would need a re-entry permit:
http://www.japan-guide.com/e/e2221.html

If you leave Japan without a re-entry permit with your student visa, then you have to surrender your Alien Registration Card, and your Visa becomes invalid.

If you need to leave Japan while still under your student visa then you would need to apply for a "RE-ENTRY PERMIT" from the Immigration office. When you leave Japan with a re-entry permit and plan to leave, you keep your Alien Registration card, when you return into Japan you show your passport with the re-entry permit and visa, along with your alien registration card.

Ah Uji answered it, the link there has all the info you need.