About Mail Stamps

I'm currently in Japan and it would be my first time to send a Letter to a person who's also in Japan. I'm sending a collection of postcards and put them in a brown envelope, if i'm going to buy for a stamp, what is the right Japanese sentence for me to use? Is there different kinds of stamps to be used n Japan? Like one for ordinary letters or for thick envelope in my case?

Postage is broken into various categories based on weight, size, etc.

For a page-sized (A4) brown envelop, it will probably cost 110 yen unless it's over a couple of ounces. It's 80 for the standard envelopes.

Just hand it to the person behind the counter.
If they look at you like ''what the heck am I supposed to do with this'', say:
''Tokyo ni okuritain desuga'' (I want to mail this to Tokyo (or wherever you want to send it)).
''futsuu yubin de'' means ''by regular mail''.

Good luck!

For a page-sized (A4) brown envelop, it will probably cost 110 yen unless it's over a couple of ounces. It's 80 for the standard envelopes.

For an envelope that you can place A4/letter size paper sheets without folding them, it's 120 yen up to 50g, 140 yen up to 140 yen, and 200 yen up to 150g, etc.

The "80 yen" above refers to the business letter envelopes often used, where you fold A4/letter size paper into three :) Even with that envelope, if it's thicker than 1cm, you have to pay a bit more.

You take it to the post office "letter/postage" counter, they'll look at the address, and probably all they want to know is whether you want it "regular" or "express mail." So if you just say "futsuu yuubin de," they she will tell you the postage.

Actually, if you take the envelope to a major convenience store such as Seven Eleven, you most likely are able to send it within 80 yen.

Ask if the store does "meeru-bin" which is a mailing service provided, not by the Post Office but, by Yamato Unyu. It should be delivered within two or three days. If you pay 100 yen extra, it will be delived by the next day.

So you go to the store and say, "Meeru-bin yatte masuka?" (Do you do Mail-bin?) and if they say yes, hand them the envelope. You will be asked to fill in a tiny paper in which you are supposed to write "shorui (documents)."

Refer to the bottom of the following site for details on prices according to the size of the envelope.
http://www.kuronekoyamato.co.jp/mail/mail.html

Btw, if you bring it to a Post Office, you can still send it for 80 yen if the envelope is within
14-23.5cm x 9-12cm
1cm thick
less than 25‚‡.
If it's the above size and less than 50‚‡, postage is 90‰~.