TV-Series
Description
Kotaro Sakazaki, a middle-aged former security guard, lost his wife and daughter Mikoko Sakazaki after Japan's economic downturn left him unemployed and drowning in debt. This devastating separation became his driving force. He first spotted Kaiji Itō in a dark alley, witnessing Kaiji bluff thugs with fake yakuza ties. Sakazaki recognized the deception and approached Kaiji, convinced the younger man could help him beat "The Bog," a rigged pachinko machine at a Teiai casino. He saw gambling not as a choice but as a desperate path to win enough money for a home and family reunion.

Initially seeking Kaiji's skills to conquer The Bog, Sakazaki later became his ally after observing Kaiji's resolve. He displayed fierce commitment during their partnership, gambling to the point of physical collapse. Following their victory over The Bog, Sakazaki used his share to buy a house, prompting his family's return. He offered Kaiji temporary shelter. However, Sakazaki grew uneasy over Kaiji's directionless existence and his daughter Mikoko's growing fondness for him. Sakazaki eventually asked Kaiji to leave, providing 3 million yen on the condition he never return—motivated by both protecting Mikoko and disappointment in Kaiji's lack of purpose.

Months later, Sakazaki reappeared when Kaiji returned to repay the 3 million yen plus 105 million yen in profit. Sakazaki angrily dismissed the 108 million yen as counterfeit and departed. Discovering the money was genuine—verified by his ability to smell authentic currency—he chased after Kaiji, tearfully begging him to come home. Kaiji declined, fleeing Teiai pursuers. Sakazaki accepted the money, which Kaiji intended as insurance for himself and his friends if captured; this windfall later made Sakazaki a target. Teiai's Yūji Endō tortured him via fingernail piercing for information on Kaiji's location, though Sakazaki was spared further interrogation when new leads surfaced.

Sakazaki also appears through the premonitory dreams of Ichijō, Murakami, Yamada, and Misawa in the spin-off "Jōkyō Seikatsuroku Ichijō," where they mistake his face for the "This Man" urban legend. These dreams feature scenarios from Teiai's Underground Casino and perspectives from Kaiji during The Bog arc, including their shared living quarters.

His name "Kōtarō" combines the kanji for filial piety (孝), thick/great (太), and son (郎), while "Sakazaki" means slope (坂) and cape (崎). He embodies a pragmatic, family-focused nature and a distinctive "dad" style, favoring comfortable, mismatched clothing like sweatpants and oversized sweaters. Serving as a foil to Kaiji, Sakazaki highlights their divergent reactions to poverty: he gambled solely to reclaim his former life and quit upon his family's restoration, while Kaiji pursued the thrill of risk. This contrast culminates in Sakazaki viewing Kaiji as "such a sad man," recognizing his inability to escape gambling's allure despite achieving freedom.