The Teiai (帝愛 lit. imperial love) Corporation is a criminal organization that facades as a financial consulting firm in the Kaiji series.
It plays as the main group that sponsors most of the major gambling events that happens under the orders of its president, Kazutaka Hyōdō.
The company main business is loan sharking and when the debtor cannot pay back, they are forced to participate in the gambling events Teiai hold, or are sent to the underground labor camp.
According to Takashi Muraoka another big source of income of Teiai comes from criminal protection as they are responsible for covering up multiple illegal and tax-evading businesses with hefty fees. Muraoka's casino is one of the illegal business under Teiai's thumb.
The company seems to be above the law as they can practice slavery and cover up multiple illegal and tax-evading businesses without being ''visited'' by the authority. It is possible that Hyōdō bribes a vast majority of government officials to make his business goes smoothly.