The story is a prequel to Fist of the North Star
On the cover of the newest issue of Tokuma Shoten´s Monthly Comic Zenon Magazine has revealed that an Anime adaptation of the Fist of the Blues Sky Manga is in the works. More details about date, staf or cast are still unknown.
Gutsoon! Entertainment describes the story as follows:
“It is just before WWII, Kasumi Kenshiro hides as a quiet, absent-minded professor teaching literature at a small women’s college in Tokyo. Once the 62nd Grand Master of Hokuto Shinken, “God Fist of the North Star,” and known has Yan Wang, or “the King of Death,” who preserved the peace in the “City of Devils.” A fighter of thugs and drug dealers, Kasumi seeks anonymity and a quiet life until the death of his lover, and former brothers, forces him to return to Shanghai to fulfill his destiny and avenge the deaths of his associates.”
Via: Anime News Network