Dear Miss Snark,
How does one go about proposing a translation?
There is a very popular series of fantasy books in Japan that have sold millions of copies, but no English translation has yet been made. Does a translator include what publishing data may be had from the book and the Internet along with the submission and query letter? Is there any other information, such as the original author's biography or a list of the other books in the series?
You've got the cart in front of the horse.
Translations are arranged by the publisher who buys the foreign language rights (in this case English is the foreign language).
The publisher or author of these popular fantasy books has a foreign rights agent. That agent shops those books to American publishers of fantasy. The American publisher acquires the rights, and hires the translator.
I attended a very instructive presentation on literature in translation about two years ago, and one of the things mentioned was how hard it was to find good translators at reasonable rates. If you're really serious about making this happen, contact the Japanese publisher, or their foreign rights agents and offer to do a translation on spec.
If you approach a US publisher or agent without owning the rights to the work, you will be treated like a crackpot.