The twisted saga of the Mishima bloodline has captivated Tekken fans for nearly three decades, but a recent Twitter thread by Tekken producer Katsuhiro Harada has unearthed shocking new information about the family’s dark legacy — including the staggering revelation that Heihachi Mishima has at least 25 children. The roots of the Mishima conflict stretch back to the original Tekken, where a young Kazuya Mishima sought revenge against his ruthless father, Heihachi, by seizing control of the powerful Mishima Zaibatsu. In Tekken 3, Kazuya’s own son Jin Kazama entered the fray, escalating the family conflict into a full-blown generational war that has persisted through Tekken 8.
But things got even more complicated with the introduction of Lars Alexandersson, Heihachi’s illegitimate son, in Tekken 6: Bloodline Rebellion, and the recent debut of Reina, Heihachi’s estranged daughter who possesses both his fierce fighting style and the enigmatic Devil Gene. While Tekken 8 and its story DLC explored these dynamics, fans were left with lingering questions — particularly around the origins of the Devil Gene and Heihachi’s mysterious lineage. Over the weekend, Harada took to Twitter (via GamesRadar) to clarify some of these mysteries.
According to Harada, Heihachi’s massive brood of 25+ children wasn’t just the result of his aggressive nature or power-hungry ambition — it was part of a calculated genetic experiment. Harada explains that Heihachi sought to disprove the theory that the Devil Gene originated from the Mishima bloodline, and so he pursued “every possible avenue of genetic research” to isolate its source.
“Heihachi never believed the Devil Gene was his doing,” Harada said. “He wanted proof — and that meant testing, offspring, and science.”
This chilling revelation reframes much of the Mishima story. Heihachi’s actions weren’t just driven by hatred or ideology, but a twisted form of self-exoneration — a desire to distance himself from the evil that consumed his son and grandson, even if it meant creating an entire generation of test subjects. While many of Heihachi’s children remain unseen in the games, this lore dump opens the door for more potential playable characters, expanded storylines, and deeper emotional stakes in future titles.
As the Mishima saga continues, one thing is clear: behind every punch and betrayal in Tekken, there’s a legacy of secrets, experiments, and generational trauma — and Harada is far from done telling that story.