Kazuya was created by Takuji Kawano. Tekken producer Katsuhiro Harada created Kazuya Mishima as a corrupted character with a "pure dark side" as opposed to his father Heihachi Mishima, who Harada identified as having a more "human dark side". The franchise's design team referred to Kazuya and Nina Williams as "the soul [or] the cool part" of the original 1994 game. Kazuya's design and characterization was influenced by a variety of sources. Kazuya's family name was taken from author Yukio Mishima, who was also used a model for the character's physical appearance. Harada compared Kazuya to a yakuza, while artist Takayuki Yamaguchi based the character's Tekken 6 costume on a robot. When describing Kazuya's personality, Harada cited him, along with Heihachi and Jin Kazama, as the violent characters of Tekken; he described the family as too quarrelsome. Denying claims that Tekken's plot is too convoluted, Harada said that its basic story is a "simple" struggle among members of the Mishima family with other characters dragged into the conflict.