JUSTIS was a Japanese street gang that was active nationwide during the 2010s. Founded by professional wrestler Kazuchika Okada and his friend "Joe" Jojima, JUSTIS originated as a vigilante group meant to battle the yakuza-backed "color gangs" that dominated Tokyo's Kabukicho nightlife district. After Okada and his girlfriend were kidnapped and tortured by the Satsuki-kai boss Scar Satsuki, Okada took a dark turn, outwardly coming to worship strength and transforming JUSTIS into a violent street gang; secretly, he hoped that his expulsion of Jojima from the gang would lead Jojima to create a new gang, defeat JUSTIS, and lure out JUSTIS' new financial backer, Satsuki. Takeshiro Komei became JUSTIS' strategist, although he also harbored treacherous motives, seeking to take control of the gang for himself. Komei and Okada recruited pro wrestlers Toru Yano, Satoshi Kojima, Hiroyoshi Tenzan, Hiroshi Tanahashi, and Tetsuya Naito into the gang; they and Okada became known as the "Six Lunatics", the powerful leaders of the organization.
In December 2016, Jojima enlisted the help of Kazuma Kiryu with forming a gang to fight back against JUSTIS, and Kiryu created the Onomichi-based Kiryu-kai. As the Kiryu-kai took down the Six Lunatics one-by-one, the gang gained new followers from both street thugs and the Lunatics themselves. After Kiryu defeated Okada, Komei revealed his intention of taking over JUSTIS and making it the most powerful gang in Japan with Satsuki's backing. Okada then revealed the true nature of his plan, defecting to the Kiryu-kai and helping them defeat Satsuki and Komei in a final battle in Kabukicho. Satsuki and Komei were arrested for their crimes, but JUSTIS holdouts continued to cause trouble, necessitating the Kiryu-kai's continued existence.