Can language school take my alien card away?

I will be graduating soon and the school is asking me to come to their office. They told me to bring my alien card. (I told them I'm not going to continue to study anymore and forced me to return to my country asap.) Am i gonna be the one to return my alien card to the immigration or they will be the one to do it?

You need to keep your resident card (�galien�h card) until you leave Japan and hand it over at the passport inspection when leaving Japan. Not earlier as you are obliged in Japan to always have your valid ID on you.

they will inform your leave (from school) to immigration office (that is school's duty). so, immigration knows that you don't go to school.
also, you can't work as part-time worker, because you are not a student any more, although you still have student zairyu card.
if you want to keep your student status, you need to find another school, probably withing 3 months (with no working).
if you don't do that, your renewal or new application will not be granted in future. (i.e. you lose the chance to stay in Japan in future.)

The short answer is no, the school cannot take away your resident card.

If/when you decide to leave Japan for good (not returning on that status any more) you will be the one to turn it in at the immigration at the airport. It is your personal ID, which you need to carry with you at all times while you are in Japan.

When you have left/finished your school, both you and the school need to inform the immigration authorities within two weeks that you�fve left the school. If you want to continue to study elsewhere, you can tell your intention to the immigration authorities, and you need to be signed up with the new school within a few months (as long as there is remaining validity on the resident status).

As far as I know, just because you finished your course, the school does not have the authority to �gforce�h you to return to your country at all.

NO!!
Under law the only people that can even request to see your resident card are the police or other authorised official. Do not under any circumstances hand over your resident card. And as noted, it is a legal requirement to carry it with you all the time anyway.

Just because they are not allowed to take your gaijin card, doesn't mean they won't. As other posters have said, do not give them your gaijin card. They may say they require it to get the details. I would provide them with a photocopy. I repeat, do not hand over your gaijin card even for them to look at.

@Ric "Just because they are not allowed to take your gaijin card, doesn't mean they won't. "
Let me re-state this - they can ask to see it, but under law you only need to provide it to a proper authority and that is limited - police or authorized official. Not having your card is illegal - they should know that.
As an example, many times I have been asked by hotels for my card and I refuse, having to explain the law that they operate under becomes tedious. There are other ID forms that work well (drivers license or passport as examples). I have (a long time ago) used my resident card as ID at the post office, and sometimes at my local city hall getting official documents, but I don't hand it over as a rule.
There is no valid reason for someone to retain your identity card (or passport) for that matter. If they did - contact the police and get it back.