Does anyone doubt if Ozawa resigned, the charges would disappear just like they did last spring ??
This is not a exactly battle between honest prosecutors and a corrupt political leader.
Ozawa is trying to reform Japan from a technocracy to a democracy. He is the only person in Japan with enough power and the will to crush the country's corrupt bureaucracy.
The bureaucracy knows that and they are trying to destroy him before he destroys them.
If the prosecutors had anything on him, they would have arrested him long ago.
Hell hath no fury like a Japanese civil servant threatened by political change.