Name Conversion

I'm not sure how to phrase this question, but I can give a scenario...

I move to Japan and eventually become a permanent resident. Will I need to change my name to japanese symbols (kanji, etc.) or is it legal to sign your name in english?

If I do have to change my name, and if there's no similar kanji etc. (I don't know the other two) version to my name, will I just have to get another?

If there is one the same or similar to "Gillmore Brian", if you could show me and say how it's pronounced, that would be great.

My computer doesn't show the japanese symbols, so if you're going to give examples, please write them in the english letters version :)

Replies appreciated. Thanks a load.

Will I need to change my name to japanese symbols (kanji, etc.) or is it legal to sign your name in english?

No, as permanent resident you do not need to change your name and can use your name in alphabet. You can optionally get a kana version of your name registered at the city hall.

Only if you become a Japanese citizen, will you be required to get a name that can be written in Japanese.