If you have scores of Japanese songs without Rōmaji (Romanized transliteration) of the texts, you can easily write out the transliteration by using the above charts, which show a Rōmaji transcript of each Japanese letter. 

   Please know that traditional Japanese language has three sets of letters (characters):

            Hiragana–Phonetic and syllabic characters. There are 46 basic characters.

            Katakana–Phonetic and syllabic characters used only for foreign words and names, loanwords, onomatopoeia, and emphasis, etc. There are 46 basic characters.

            Kanji–Chinese characters that show the meanings of each word.  Many of them have been simplified and modified from the traditional Chinese characters to the Japanese Kanji characters. Each character could have multiple pronunciations. Two to three thousand Kanji are commonly used in Japan.

   Most of the song scores use only Hiragana and Katakana even though the original poem would have been written with a combination of all three characters.

 

Notes:

1. Hiragana は(ha) and へ(he) are pronounced “wa” and “e” respectively, when they are used as particles in sentences. Particles are monosyllable words that usually come after nouns and often work similarly to prepositions or “postpositions” to be more accurate.

2. Scores published before 1946 were using the old (historical) kana orthography. You must find the poems written in the modern orthography in order to figure out transliteration using these charts. 

3. There are some other Katakana combinations such as ファ(fa), ウィ(wi), スイ(si), etc., which were created to indicate non-Japanese sounds.  The chart above does not include these variations.

4. Letter う/ウ(u) is pronounced as a part of a long ō, when it is preceded by an o vowel.                                 相撲 (すもう)　sumō (sung as [su mɔ:], not [su mɔu])        

5. A small つ/ツ(tsu) indicates that there is a stoppage and the following consonant is doubled.                      いった (itta)     かっこ(kakko)     ぺット(petto)