My username is a lie, I do speak some Japanese. I'm still learning, though. I like to romanize lyrics!
This is what I do: Japanese lyrics from j-lyric. To romaji with nihongo.j-talk set to Spaced and rōmaji (I don't trust the roumaji). Open up Text Mechanic's Find and Replace tool in two windows. Paste kanji in one window (not changing anything, just to compare), and romaji in one. While listening to the song, start replacing according to my own preferences.
| ā → aa||yasashi sa → yasashisa (merging ~sa)|| ichiko → ikko (counters)|
| ī → ii|| shi ta → shita (merging ~ta)|| ni nin → futari (counters)|
| ū → uu|| shi te → shite (merging ~te)||mahoutsukai → mahou-tsukai|
| ē → ee|| shi nai → shinai (merging ~nai)|| donna → don'na|
| ō → ou||shi tai → shitai (merging ~tai)|| da kara → dakara|
|oukii → ookii (ou to oo in some words)||sure ba → sureba (merging ~ba)|| n da → nda (merging n~)|
| 10 → juu (numbers)|| shira zu → shirazu (merging ~zu)|| na ndarou → nan darou|
| '' '' → 「」||shira nu → shiranu (merging ~nu)||wo → o|
and so on.
I have an unhealthy hatred towards ilyricsbuzz.
Will romanize upon request.