Kiryu Mamoru, a subordinate boss of the Tomogashira Group, earns a living through the shady business of "yamikin" or underground lending. He preys on desperate customers who cannot get loans from legitimate lenders, charging exorbitant interest rates of 30% in 10 days or even 90% in some cases, in violation of the law. With the backing of his yakuza group, he employs extremely vicious and unethical methods...