According to Kyo’s designer, his final design was inspired by Jo Yabuki from Ashita no Joe, and Akira Fudo from Devilman.
Contributed by DrakeVagabond
Heavy D! is inspired by the SNK boxing game Main Event. He was named after the American rap artist of the same name from the rap group Heavy D & The Boyz. However, to avoid any possible copyright issues, they added an exclamation point at the end.

His pet cat, Puu, was also named after one of the developer's cats.
Contributed by DrakeVagabond
Choi Bounge's original design was changed at the last minute to avoid distinct similarities with horror film character Freddy Krueger from the A Nightmare on Elm Street franchise.
Contributed by DrakeVagabond
The development team intended for Ralf and Clark to be shirtless, keeping them in line with their appearance in Ikari Warriors. However, the higher-ups ordered them to update their designs to look more modern.
Contributed by DrakeVagabond
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In the original Japanese release, opponents expel blood when hit. This was changed to show small hit markers instead when released overseas.
Contributed by ProtoSnake