From the liner notes

When a local gambling house kidnaps some peasants because they failed to pay their debts, a rival gambling house pays their debts and sets them free. But it's really all just a plot to enlist Ichi's aid in eliminating the competition, and once that's been attended to, the master of the surviving house of chance grabs more and more power-- and more and more cash from the hapless farmers. Even a blind man can see that Justice must be done!