Shodai Nekketsu Kouha Kunio-kun/Cheats
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7E010EFF: freeze HP at 255
This code locks your HP at 255. Since this is not a normally achievable number the health bar may fluctuate between almost empty and almost full as you take damage, but the code's effects will still work.
7E0110FF: Freeze KI at 255
Now you can spam speed and power enhancements all you like if you feel you're having a hard time.