Ninja Cop Saizou is a Japanese-exclusive NES title that features Saizou, a ninja working as a police officer, combining the stealth aspects of a ninja with police investigation and action. The game's gameplay likely involved navigating levels, solving puzzles, and fighting enemies with ninja techniques.  The developer and further specifics regarding its history and popularity require additional research.

Ninja Cop Saizou (Japan)

Niji no Silk Road (Japan)