Kazutaka Hyōdō is president of Teiai Corporation, a powerful financial consulting firm that sponsors deadly underground gambling tournaments where destitute individuals face lethal risks. Extreme wealth has driven him to madness, rendering conventional hobbies dull. He funds these tournaments to derive pleasure from observing participants struggle against terror and despair. He openly acknowledges possessing a low valuation of money, believing true wealth is the ability to maintain luxury regardless of circumstances, such as wartime, viewing money primarily as a means to build an underground bunker empire. His behavior includes bizarre and disturbing stunts, often humiliating employees for personal amusement, such as forcing them to drink wine from a bowl containing his feet.

He exhibits clear favoritism toward his eldest son, Kazuki Hyōdō, while frequently neglecting his youngest son, Kazuya Hyōdō. His parenting is detrimental to both sons, reprimanding them for circumstances beyond their control. Despite his generally cruel demeanor, he occasionally displays uncharacteristic kindness in a positive mood, though minor irritations like a pebble can shatter this. He harbors a soft spot for small animals like kittens, puppies, and birds. He disdains most films, with exceptions for the works of Alfred Hitchcock and Akira Kurosawa.

He first appears in silhouette during the Espoir arc's conclusion, observing Kaiji Itō's survival. His full debut occurs after the Steel Frame Crossing gamble, where he invites Kaiji to play E-Card. After Kaiji defeats Yukio Tonegawa, he subjects Tonegawa to the Kneeling Plate Grill punishment and has him escorted away. Exhausted, he attempts to retire but is stopped by Kaiji, agreeing to a game of Tissue Box Raffle. Drawing on experience as a shyster, he detects Kaiji's foul play attempt and subtly imposes favorable rules, winning and enforcing the penalty: amputating the four fingers on Kaiji's left hand while confiscating all prior winnings.

Later, he monitors Kaiji's challenge against The Bog via live feed while visiting an underground labor camp, instructing Seiya Ichijō to prevent Kaiji's win and threatening consignment to labor if The Bog loses. Following Kaiji's victory over Kazuya in One Poker, he becomes furious and grief-stricken, interpreting the mercy shown by Kaiji, Mario Garcia, and Chan in saving Kazuya as self-preservation and a rule violation. He declares their win invalid, establishes a Teiai manhunt division to recover the money and capture the trio, and spends his days inconsolable in a bed adjacent to Kazuya's hospital room where Kazuya lies comatose. Frustrated by his inability to awaken Kazuya despite vast resources, he fluctuates between depressive episodes and fits of rage. After weeks without manhunt progress, he summons the division leader, Yūji Endō, to the hospital and orders him to commit suicide by jumping from the window. Yoshihiro Kurosaki intervenes, warning of potential negative impacts on Kazuya's condition, rescinding the command.

His younger son, Kazuya Hyōdō, works as a novelist and high-ranking Teiai employee facing widespread company disdain. He operates "Kazuya Corporation," specializing in covering murders as suicides or accidents. He embodies a tragic antagonist role, openly detesting his life and believing he has never experienced genuine friendship or love due to others' sycophancy driven by his father's influence. Convinced humans are inherently detestable and prone to betrayal, he designs deadly games testing human bonds, serving as novel inspiration. Despite a sadistic and arrogant exterior, he harbors profound misery stemming from envy toward Kazuki, perceiving himself perpetually ignored by his father and company. He struggles with low self-esteem, believing everyone hates him, and misunderstands an incident where his mother saved Kazuki first during an accident as preferential treatment. This fuels his gambling addiction, used to validate his worth and vent frustration.

Kazuya first encounters Kaiji at Takashi Muraoka's underground casino, loaning Kaiji money for the Mine Field Game, stipulating amputation if unpaid. After Kaiji's victory, Kazuya offers higher-stakes gambling, transporting him to a graveyard containing a pre-prepared grave bearing Kaiji's name and compelling him to sign a contract outlining post-mortem body management. They relocate to Kazuya's restaurant where he presents the Rescue Game experiment. Later, during the One Poker gamble in a warehouse, Kaiji insists on including Chan and Mario as support, a condition Kazuya reluctantly accepts. Following his defeat, Kazuya falls from a great height as the penalty but is saved by Kaiji, Chan, and Mario. He is left unconscious, prompting Kazutaka's vengeful manhunt. Kazuya remains comatose and hospitalized, with Kazutaka maintaining a constant vigil.

In spin-off media like *Chuukan Kanriroku Tonegawa*, Kazutaka's erratic and demanding behavior toward subordinates like Yukio Tonegawa is depicted, showcasing his propensity for imposing unreasonable stress. An anecdote reveals that when Kazutaka desired to travel to Hawaii, Kazuya diverted the private jet to the Maldives instead.