Kazuma Kiryu is the primary playable protagonist of the Yakuza franchise. Born in Yokohama, Japan in 1968, Kiryu was raised in the Sunflower Orphanage following the deaths of both of his parents at a very young age. The orphanage's main benefactor Shintaro Kazama took young Kiryu under his wing, acting as a father figure and later inducting both Kiryu and his friend Akira Nishikiyama into the Kazama yakuza family, a subsidiary of the powerful Dojima Family and its parent Tojo Clan.
As a yakuza, Kiryu built a reputation for himself as the "Dragon of Dojima" thanks to his unyielding resolve and incredible ferocity as a melee fighter. Stoic and trustworthy almost to a fault, Kiryu constantly strives to uphold his personal code of honor while protecting those he cares about, despite his own inescapable affiliation with Japan's criminal underworld.
In this series prequel, twenty-year-old Kiryu works for the Dojima Family in 1988 as a debt collector. When a businessman shaken down by Kiryu turns up dead inside a hotly contested piece of undeveloped real estate known as the "Empty Lot," Kiryu must prove his innocence by leaving the Dojima Family in order to investigate the murder on his own.
In order to protect his sworn brother Nishikiyama, Kiryu assumes responsibility for the murder of yakuza boss Sohei Dojima in 1995. After serving a ten-year prison sentence, Kiryu is released only to find Kamurocho's entire underworld in chaos due to a conspiracy revolving around the theft of ten billion yen, as well as the murder of the Third Chairman of the Tojo Clan, Masaru Sera.
During the game's finale, it is revealed that Kiryu's parents were killed by Kazama, who subsequently adopted the orphaned Kiryu in accordance with a longstanding yet rarely observed yakuza tradition of raising the children of one's victims as a form of honorable penance.
Six months after the events of the first game, the Fifth Chairman of the Tojo Clan, Yukio Terada, is assassinated. As he investigates this high-profile murder, Kiryu is plunged into a new conspiracy born from the Tojo Clan's massacre of the Korean Jingweon mafia twenty years prior.
Kiryu abandons the life of a yakuza to run Sunshine Orphanage in Okinawa, but he is reluctantly pulled back into the shadows of Japan's underworld when an impending real estate deal threatens the orphanage. Kiryu heads back to Kamurocho to address the problem, but soon finds himself in over his head as the specter of yet another clan war looms.
Kiryu is still running the Sunshine Orphanage, but finds himself drawn into yet another convoluted series of events when convicted murderer and Tojo Clan member Taiga Saejima washes up onto the nearby shoreline. Kiryu returns once again to Kamurocho, meets up with the game's other protagonists, and classic Yakuza action ensues.
In this zombie-themed (and non-canon) spin-off title, Kiryu must fight for his life within the bowels of a Kamurocho overrun by the undead. His special weapon is an anti-materiel rifle.
Living under an assumed name, Kiryu tries to make a new life for himself as a taxi driver in Fukuoka. However, when he is approached by Daigo Dojima, the patriarch of the Dojima Family, Kiryu discovers a new conflict brewing between the Tojo Clan and the Omi Alliance that could bring a bloody end to the cease-fire treaty between them, forcing Kiryu to intervene for the sake of his friends.
After the events of the previous game, Kiryu is thrown in prison for three years. He returns to find that Haruka missing from the orphanage, and returns to Kamurocho once again to find her. Not only does he discover Haruka had a son out of wedlock, but his search to find the boy's father leads him to Onomichi in Hiroshima, where he once again finds himself embroiled in Yakuza politics, while Chinese and Korean mafia groups take advantage of the chaos in Kamurocho.