Hiryuu no Ken Gaiden, a Japanese Game Boy title, might be a spin-off or side-story in the Fist of the North Star universe, drawing from the popular manga and anime. The game likely features action-based fighting mechanics, similar to other beat 'em up titles on the Game Boy.  Its specific publisher and release date require additional research; however, based on the source material's popularity, it might have been a title developed by a company aiming to create a game for fans of the series.

Hiryuu no Ken Gaiden (Japan)

Hercules no Eikou - Ugokidashita Kamigami (Japan)