This song is included in this channel's Japanese song playlist
https://www.youtube.com/playlist?list=PLjDc9r7oZzO6NiLl_amQwEDB-EA0ek00g
愛人 meaning "A mistress", won the Grand Prix （グランプリ）
in 1985. The other two Grand Prix wins by Teresa Teng were
for her 「つぐない」 (Tsugunai) in 1984 and 「時の流れに身をまかせ」
(Toki no Nagare ni Mi o Makase) in 1986. This was the first time in Japanese music history that any singer had won the Grand Prix three years in a row.
**This video clip is authorized by the bilibili website to upload
and add Romaji and English translation.