This game is also available on Game Gear.
Retro Game Cheats for Shinobi 3 (Mega Drive)
Effect: Infinite shuriken
When:
In the Options Menu
How:
Set the number of shurikens to "0", then set the sounds option to "Shuriken", then highlight the number of shurikens again (and wait for a few seconds) to change "0" in to Symbol Of Infinity
Submitted By:
Unknown
Effect: Infinite health
When:
In the Options Menu
How:
Highlight SE Selection, then press B to play "He Runs", "Japonesque", "Shinobi Walk", "Sakura", "Getufu" (in that order)
Submitted By:
Unknown