If you wish to play a game on NHN's Hangame.co.jp, it's required that you sign up. The obvious problem is the language barrier since it's in Japanese. So if you need help, this is the place to get it. First of all, the easiest way to find the registration page is to go to the Gunstrike homepage, and then click on the picture to the left (see picture to the left).
This will bring you to the registration page, very normal looking. Luckily, since it is in HTML, the source code is also in English. Thus the input boxes within the form are all labeled accordingly (except two, but don't worry about them). Now looking at the boxes from top to bottom, enter the correct information as it pertains to each:
Once you have those filled in, simply don't touch the last two boxes (unknown meaning, although the boxes are labeled answer1 and answer2). Click the image at the bottom with the little blue arrow to submit your data. You will receive an email containing your information, an advertisement link, a help link and a "reject_revmail" link (either it disables the newsletter option, or deletes your account so don't click it unless you're testing). You can log in immediately thereafter.
Sadly, if you aren't Korean you cannot register on Hangame.com. The registration process requires a Korean citizen ID; thus anyone not from the country or who did not receive an ID (such as children who emigrated) cannot play their games.