I have to agree with SunshineSlayer ^ I'm not sure if SELs are what Avex is looking for, though I'm not denying you've done a good job with them.
Nevertheless, if you really ARE serious about pitching your SELs to Avex, you should follow your dream!
Just be warned: there's no way they are even going to consider you unless you get a few things together first.
Not to be mean, this is just constructive criticism, (I can't help it, English is my strong point) but this is the MINIMUM I would do to spruce up your application:
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The letter's really unprofessional, full of unneeded information and fluff. It's going to be hard for Avex to take you seriously when you're gushing so much. Also, there are a ton of spelling and grammar errors that you should fix up.
Choose one language: Japanese or English. Don't write in English and throw random Japanese phrases in there, it detracts from the natural flow of the letter. Write the whole thing in English, or the whole thing in Japanese.
Emoticons -- no way! Those are very very unprofessional. Do you write emoticons in your reports for school? Of course not, because they don't belong in a report, and they don't belong in a business letter either.
You need to address Ayumi as "Hamasaki Ayumi," not "Ayumi-chan."
In your letter, you don't need to mention that you speak Japanese, are a choreographer, et cetera. Things like that belong on a seperate resume where you would list your education, contact information, previous jobs, and references, for instance. The point of the letter is to pitch your idea to them, NOT to talk about yourself and how much you love Ayu.
Last but not least, you have to make sure the SELs you send them are arranged in a portfolio. That includes a demo tape, and a short cover letter if you please.
You might want to get someone experienced to help you put the whole thing together. It's not a matter of "Oh, I think I'll write a quick letter to Avex and see if they like it!" If you really care about your idea, you'll want to take time on it, right?
Basically, you'd have to make it very professional for them to even take a look at it before tossing it out the window. Remember, this is AVEX you're pitching this to -- they probably get a million crappily written proposals from would-be singers, writers, and producers a day. You have to make yours very well-done so it will stand out.