The first thing you need to do in order to play the free "Up to Level 20" trial of Dragon Quest X is register a Square Enix account, which you will find on the side in a big blue bar!
https://secure.square-enix.com/account/app
Confirm that your region you are registering for is Japan, or it won't work!
You will then "read" a terms of agreement. Just check the mark at the bottom!
You will then confirm your email address. If you have a pre-existing English Square Enix account, DO NOT USE THAT EMAIL! That means if you've played Final Fantasy XIV or Final Fantasy XI, don't use your Email associated with those accounts. I recommend making a new Email account to exclusively use for Japanese things (or just this, of course!).
Click the yellow highlighted link to continue on to the account creation process.
Now that your next step is up, you have to input your username of choice. I recommend using your standard name, but adding the letters "jpn" at the end for an easy memory check! Add a password and birthday, then move on.
You are now on the last part after continuing to click on! You need to put in information. Click a gender, but now comes a tough part. You need to put your name in with kanji or hiragana, then your name again written phonetically. If you don't know what to do, just use this name: copy and paste 福原 as your surname and 愛 as your given name. Then for the next line, paste フクハラ for your surname and アイ for your given name. Then, you will need to fill in your zip code. To save you googling, use mine! 980-0811. Click the box below it to autofill in your county and city. Then simply paste any kanji whatsoever into the street address and you're good to go.
A few more screens of confirmation and there you go! You have a Japanese square enix account! This is all you need at the moment to play the free "Up to Level 20" trial! Check out the next guide to figure out how to do that.