Heihachi proceeded to throw five-year-old Kazuya off a cliff. That same year, Kazuya confronted his father after learning of his mother's death, but he was defeated almost immediately by him. When her cause seemed lost, she fell into a series of illnesses, and was eventually taken over by a demonic alter ego which attempted to kill Heihachi. Unbeknown to Kazuya, his mother had been tasked with stopping Heihachi from going down a warmongering path at all costs. Then, Kazuya's mother was killed by Heihachi. First, his beloved grandfather disappeared (Kazuya would later discover he was imprisoned by Heihachi under the family temple, after Jinpachi failed to retake the Mishima Zaibatsu from Heihachi, who had previously launched a coup against him). Kazuya's life took a turn for the worse however when he was five years old. Kazuya's mother loved and doted on him, as did Kazuya's grandfather, Jinpachi Mishima, who also taught him Mishima Style Fighting Karate from a young age.
Kazuya was born the son of Heihachi Mishima and Kazumi Mishima and raised on the Mishima Estate, the Mishima Clan's enormous aristocratic home in Japan. 3.13 Fist of the North Star LEGENDS ReVIVE.