Question: I am planning to study abroad in Japan in two years through my college for a year at a Japanese speaking university. I also have goals/aspirations to one day work/live in Japan. Is it weird/acceptable to give myself a kanji name based off of meaning or sound of my current name? My name is Ruth which means "friend" and "beautiful" so I was thinking of 朋麗 (ともれい). Or, I could use kanji based off of my sound to have a name that means 'dragon state' or "state of the dragon" (I was also born in the year of the dragon so it may be fitting) but sounds like Ruth 竜州 (りゅうす）. I know a closer approximation would be ルース, but I like the idea of my name meaning dragon if I were to go that route. I also have an idea for my surname, which means "gentle beauty" and I came to the kanji 泰美 （やすみ). So either 泰美竜州 or 泰美朋麗. Is it weird for foreigners to do this when they move to Japan or Study abroad in Japan? I know some people who came to study abroad in the US from China and Korea and they both took American names. Is the reverse true for in Japan? Can I do this if I'm expecting to work in Japan? Could I use this name on legal documents in Japan if I did choose to use a kanji name? I'm really curios about the whole prospect.

Answer: 
Firstly, for legal documents you should always be writing your name as it appears on your passport. When documents ask for your name, age, etc. they're trying to confirm your identity. If you supply a false name then they won't be able to tell whether you're a real person or not.

As for the social part, I think it's up to the people who will be calling you what you want to be called. After you've made some friends at your new University, ask them if it's weird for you to take on a Japanese alias. I had one friend who came to work in Australia from Korea who had also worked / lived in Japan. He has unique Japanese, Korean and English names.

I hope you have a great trip!
I think it's more natural to write your name in English form as we're familiar with English, but I like your try.
The reasons we call ourselves in another name are
1: 70% we find it fancy
2: 30% some people are difficult to be called with the original one like りゅ　りょ sounds