Kotaro Sakazaki is a middle-aged man who worked as a security guard until he was fired from his position at the Teiai Group. His wife and daughter left him because of the severe financial strain he experienced, a loss that becomes the driving force behind his actions. He is deeply motivated to win the enormous jackpot offered by the Swamp, an elaborate pachinko machine controlled by Teiai, so that he can buy a house and reunite with his family. Sakazaki is perceptive and shrewd; when he first meets Kaiji Itō in a dark alley, he sees through Kaiji’s bluff and immediately recognizes him as a gambler with the potential to take on the Swamp. He initially approaches Kaiji with the aim of using his skills for their mutual benefit, but as the mission unfolds Sakazaki transforms from a desperate, solitary figure into a dedicated ally. He joins forces with Yumi Ishida and Yukio Tonegawa, who also bear grudges against Teiai, and together they form a team determined to bring down the organization. Sakazaki’s role is essential: he provides the initial funds by stealing money from Teiai, supplies insider knowledge he gained as a former employee, and participates directly in the high-stakes dice game Chinchirorin and the final confrontation with the Swamp. He demonstrates unwavering resolve and a willingness to put everything on the line, including committing a second theft to secure the resources needed to complete the plan. Though not a flashy or instinctive gambler like Kaiji, his loyalty, courage, and quiet determination make him a cornerstone of the group. Over the course of the story, Sakazaki develops from a man solely focused on personal redemption into someone who fights alongside others for a common cause, finding renewed purpose in the struggle against a corrupt and oppressive system.