"GOODBYE" is the title track of advantage Lucy's third single, released in 1999; it appears (in a slightly different version?) on their first album FANFARE (ファンファーレ, 1999) & their 2001 compilation album Have a Good Journey.
I'm not the first person to romanize these lyrics, but I prefer my version. (For the purpose of being comprehensive there's also an...interesting interpretation on jpopasia complete with unedited google translation, which I'm not going to link here because that person was trying in good faith & I don't want to be rude.)
( so long, farewell, auf wiedersehen )
* Some edits have been made to the kanji version of the lyrics, primarily in terms of line breaks; also, in the last few lines, every lyric source I can find has "鮮やかにね" (azayaka ni ne), but every audio source I can find has "軽やかにね" (karoyaka ni ne). I'm not a translator so I have no idea how much impact swapping "brightly/vividly" for "lightly/easily" has on the lyrics, but... ¯\_(ツ)_/¯
I'm not the first person to romanize these lyrics, but I prefer my version. (For the purpose of being comprehensive there's also an...interesting interpretation on jpopasia complete with unedited google translation, which I'm not going to link here because that person was trying in good faith & I don't want to be rude.)
( so long, farewell, auf wiedersehen )
* Some edits have been made to the kanji version of the lyrics, primarily in terms of line breaks; also, in the last few lines, every lyric source I can find has "鮮やかにね" (azayaka ni ne), but every audio source I can find has "軽やかにね" (karoyaka ni ne). I'm not a translator so I have no idea how much impact swapping "brightly/vividly" for "lightly/easily" has on the lyrics, but... ¯\_(ツ)_/¯