At least two acts have recorded under the name Crystal King:

1) クリスタルキング(Crystal King) are a Japanese rock duo who were first active in the 1970s. They are known in the west for performing "Ai wo Torimodose!", the theme tune to the anime Hokuto no Ken.
The band was formed by Musshu Yoshizaki in 1971, who was joined by a second vocalist, Masayuki Tanaka, in 1975. Other musicians to have played with the band include Yamashita Michio on guitar and Nomoto Hidetoshi on bass. They made their major label debut in 1980.

Katsumasa “Monsieur” Yoshizaki [ムッシュ吉崎勝正] - Lead Vocals
Masayuki Tanaka [田中昌之] - High Vocals (left in 1986)
Michio Yamashita [山下三智夫] - Guitar
Hidetoshi Nomoto [野元英俊] - Bass
Funky Sueyoshi [ファンキー末吉] - Drums
Hiromi Imakiire [今給黎博美] - Keyboard
Kimiharu Nakamura [中村公晴] - Piano

2) Crystal King is a Dominican singer-songwriter responsible for "You Deserve", a 2016 charity single in memory of the victims of Tropical Storm Erika. (Story at IN-SPIRE LS' #MusicMatters.) Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.