[KyleGoetz]

Originally Posted by masaegu

In case someone is wondering how musical pitch notation (A, B, C, etc. ) is expressed in Japanese, we use the old イロハ syllabary.

イ = A
ロ = B
ハ = C
ニ = D

長調（ちょうちょう） = Major
短調（たんちょう） = Minor

Thus, the 「ニ長調」 in OP's question translates to "D Major" in English.

Iroha - Wikipedia, the free encyclopedia

That's cool. Thanks!