Is Sunset Song a plagiarism of Thousand Queens Songs

Not a copy.

The original song is the Japanese song "Yuyaki no Kyo" by Kondo Manohiko, then there were covers of Thousand Queer Songs and Sunset Song, but Thousand Queer Songs predates Sunset Song.

Sunset Song is the theme song of Heroic 3's Sunset Song, then later there was a Mandarin version of Promise in the Wind, sung by Yijun Li.

Song of the Setting Sun is a single released in February 1989 by Japanese idol superstar Kondo Shinhiko, with lyrics by Akira Otsu and music by Yasuji Magaino.

Yuyaki no Kyo (夕焼けの歌), like a strange wind, will slowly blow away some of one's bad moods. Its perfect melody not only conquers us because of the ****ing sound, but mainly because there are more versions of it, and it sounds and feels different. Some versions have lyrics that are philosophical in their vulgarity and thus more seductive.

Baidu Encyclopedia-Mahiko Kondo