Akira Nishikiyama is Kiryu's sworn brother. They grew up together at the Sunflower Orphanage. He belongs to the Dojima Family alongside Kiryu, active as a hot-blooded young yakuza. He supported Kiryu at the risk of his own life, such as struggling to find money for his younger sister's surgery; to him, Kiryu was more than a real brother. He is Kiryu's irreplaceable best friend.

Kazuma Kiryu is the protagonist of the 'Yakuza' series. With the 'Rising Dragon' tattooed on his back, he is the legendary yakuza feared as the 'Dragon of Dojima'. He possesses a strong conviction to 'help the weak and crush the strong', overwhelming power, and a chivalrous spirit loved by all. Raised in the Sunflower Orphanage, he met his lifelong friend Nishikiyama there. He later entered the yakuza world and rose to prominence in the Dojima Family of the Tojo Clan.

Reina is the proprietress of the high-end club 'Serena' on Tenkaichi Street in Kamurocho, Tokyo. She has known Kiryu and Nishikiyama since they were young members of the Dojima Family, providing them with one of their few places of peace and relaxation.

Shintaro Kazama is the Patriarch of the Kazama Family and the foster father of Kiryu and Nishikiyama. Once feared as a legendary hitman, he is a man of deep integrity who values honor and is admired by many yakuza as a 'man among men'.

Osamu Kashiwagi, as the Captain of the Kazama Family and Kazama's right-hand man, was a formidable yakuza feared in Kamurocho. Always calm and loyal, he watched over Kiryu and Nishikiyama as an older brother figure while supporting the organization.

Goro Majima is a hyper-violent yakuza feared as the 'Mad Dog of Shimano', yet he lives strictly by his own code of honor and aesthetics. Majima is incredibly loyal, quick-witted, and possesses a cunning side. He calls Kiryu 'Kiryu-chan' and recognizes him as a lifelong rival, while also acting as a great supporter who saves him from crises.

Futoshi Shimano is the Patriarch of the Shimano Family. Known for his massive build and ferocity, he is a major yakuza figure nicknamed the 'Man-Eating Tiger'. He is also Majima's oath father and the man responsible for the birth of the 'Mad Dog of Shimano'.

Sohei Dojima is the Patriarch of the Dojima Family. He is the oath father of Kiryu and Nishikiyama, a yakuza with cold-blooded brutality and a greedy ambition for power.

Ryuji Goda is the Chairman of the Go-Ryu Clan, a subsidiary of the Omi Alliance. He is known as the 'Dragon of Kansai'. As one of Kazuma Kiryu's greatest rivals, he is an immensely popular yakuza who is both boisterous and deeply honorable.

Nishida is a junior member of the Majima Family. While he is a long-suffering man constantly at the mercy of Goro Majima's unpredictable actions, he is known as a rare man of common sense who admires his boss more than anyone.