The antagonist of the original Yakuza was voiced by Kazuhiro Nakaya, who later went on to voice Ichiban Kasuga, the protagonist of Yakuza: Like A Dragon. The two characters also have the same koi tattoo, leading fans to speculate on the parallels between both characters, but aside from their voice actors and tattoos, there are only surface-level parallels.

The first Yakuza game features a recording of the Christian hymn "Amazing Grace", and Yakuza 2 features the Christmas carol "Silent Night, Holy Night". Each song is played during their respective game's end credits. Both games were set around December which is probably why the songs were chosen.

The original English dub voice actor for Kazuma Kiryu, Darryl Kurylo, received a copy of the first Yakuza game after starring in it. Kurlyo played the game with his son for a brief period just so he could get a feel for how his voice work was implemented into the game. While Kurlyo was looking forward to reprising the role in future games, Sega decided against producing English dubs for the series at the time and only providing subtitles, a decision that Kurlyo supported due to the expenses from dubbing delaying the release of the game. His son Bailey Kurlyo kept playing the game on his own and finished it in just a few days, becoming one of his favorite games and turning him into a longtime Yakuza fan, while Darryl never kept up with the story of the series after the first game.

Darryl Kurylo, who originally voiced Kazuma Kiryu in the English dub of Yakuza, also voiced many generic enemies including their groans and grunts throughout the game.