Where can you get a list of Japanese letters from A to Z?

There's no such thing. The Japanese writing system includes Kanji characters, which are ideographs like Chinese, and a syllabary; actually, two--Hiragana and Katakana. Hiragana is for "spelling" words of Japanese origin, and Katakana is for spelling words of foreign origin (such as English). But the characters include the vowel. There is one "letter" (not a letter but a character) for the sound ka, one for ki, and ku, ke, ko; same for na, ni, nu, ne, no, and so on; see the charts linked below. It would take four of those characters to write "Hiragana."

Many English sounds do not exist in Japanese, and there is no character for them.

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