你

你 is the chinese character pronounced nii (ニイ) and meaning you in English (あなた in Japanese).

This Japanese song is an acknowledged heard‑by copy of another unspecified song.

Facts

1. In this compilation’s heavy booklet, with lots of information and credits, it is written 信楽順三採譜 which means that 信楽順三 did not really compose it but copied it (by ear). Like acknowledged plagiarism. If this fact is not hidden away, plagiarism or rip‑off are too harsh words.

2. JASRAC (063-2937-3) says this is 台湾民謡（ＰＤ） Public Domain from Taiwanese folklore (singer’s country).

3. The very famous Vietnamese song “Không !” has same music. Lyrics are not really translation. The theme of breaking up is similar mostly inspired by the sad tone of music.

Source research

☞ V. case : Vietnamese song → Japanese song

“Không !” was composed by musician Nguyễn Ánh 9 (lyrics either by himself or by Sỹ Đan, not this Sỹ Đan).

(According to some biographical texts I have read during my research) This song was written in the 70’s during a trip to Japan with singer Khánh Ly.
During this trip, he composed the song and then could have been heard by 信楽順三 on a stage or whatever.

☞ T. case : Taiwanese folklore song → Japanese song → Vietnamese song

My current research status shows it’s rip‑off of the Vietnamese song “Không !” during the time the writer was with Vietnamese singer on Japan tour but (less likely) it may as well be a Taiwanese song that was both used as Japanese and Vietnamese songs.

But as I don’t know Taiwanese music as much as Vietnamese and Japanese, …
If someone has knowledge of Taiwanese music, it would be quite easy to know if this is from a folklore song or not. And a folklore song would obviously be the correct source as being older than a Vietnamese song of the 70’s.
Then things would then rather be as JASRAC says !