It is not peculiar to Japanese culture, but typical of all human societies, that if someone tackles you to the ground and punches or throttles you, you are allowed to use any level of force you choose to stop them.
This is called "self-defense."
Nehemiah Fischer apparently decided to imitate Trayvon Martin, and achieved a similar result.
The only place George Zimmerman could back up was into the sidewalk.
Officer Ironman had all sorts of options, after he provoked the ensuing trouble.
And, BTW - Zimmerman didn't provoke the fight...