In the Guyver anime and manga series, the Cronos organisation had established a Japanese branch in Tokyo where they conducted extensive research into new Zoanoid optimization procedures. This branch was established when Cronos bought out Max Pharmaceuticals, a medical technologies firm owned by the Makishima family. Genzo Makishima, the brother of the company's president, forced Max into bankruptcy and allowed Cronos to seize control, who then appointed Genzo as the head of the company after he had murdered his brother and his wife, adopting their son Agito and tutoring him as his protégé.
As far as the public are concerned, Max Pharmaceuticals remains as it always has, but the company has merely been turned into a front for Cronos. Using the resources provided by Max, Cronos have made themselves an influential presence in the Japanese business world and have abused this influence to the utmost by planting operatives in key positions among the media and law enforcement. That way, Cronos can carry on "inducting" new personnel and test subjects without interference from the police or any other official agency.
At the beginning of the series' events, Marmot stole the three Guyver units that Cronos had uncovered at Relic's Point. Cronos Japan dispatched several Zoanoid troopers to recover the units and kill the renegade and they tracked him to Mount Narisawa. The mission turned out to be a complete disaster: the incomplete Zoanoid had killed itself and the G-Units were scattered. Of the three units, one was recovered in a damaged state and another was activated by high-school student Sho Fukamachi. With the third unit unaccounted for, Cronos targetted Sho for capture and sent multiple Zoanoids after him, but with the power of the Guyver at his disposal he proved to be a difficult target for ordinary Zoanoids.
Cronos inspector Oswald A. Lisker inadvertantly activated the recovered unit and decided that he would capture Sho himself. Due to the damaged state of his Guyver unit, Lisker's control medal malfunctioned in the middle of combat, allowing Sho to defeat him. It was not until Cronos Japan was placed under the management of Richard Guyot that it would succeed in eliminating Sho, which was accomplished by turning failed manager Genzo Makishima into the first anti-Guyver Zoanoid, Enzyme. Enzyme's corrosive blood was able to swiftly dissolve the bio-boosted armour and he removed Sho's control medal, causing Sho's Guyver to eat him alive.
With the control medal recovered, it seemed that Cronos had won. The medal was placed under examination and Sho's high-school friend Tetsuro Segawa had been taken prisoner. What Cronos were unaware of was the Guyver's incredible regenerative capacity, which seemed capable of reconstructing Sho's entire body from only a few strands of DNA left on the control medal. Not only did the Cronos personnel have to deal with the rebirth of Guyver-I, but also the arrival of Guyver-III, who had suddenly appeared within the complex and had begun tearing it apart, destroying the Zoanoid development labs and killing every Zoanoid in sight.
Guyver-I fully regenerated and proceeded to attack everything in front of it. It carved a path of destruction through the building until it reached the detention level where Tetsuro was being held, and at that point, Sho seemed to regain consciousness. Sho was unaware of everything that had occurred since his battle with Enzyme at Narisawa Lake up to his freeing Tetsuro, but with his consciousness restored he focused on getting Tetsuro out of the building safely. Along the way, Sho and Tetsuro encountered Guyver-III who informed them that he had activated the complex's self-destruct sequence. Before making their escape, the Guyvers confronted Richard Guyot on the tower's helipad just as the commander was about to leave on an escape chopper. It was then that Guyot first revealed minor details regarding the Creators, the alien beings who created the human race as a basis for the ultimate bio-weapon, the Zoanoid.
As Guyot attempted to flee, Guyver-III triggered a bomb he had planted on the chopper, destroying it and seemingly killing Guyot. Seconds later, the dark Guyver fled the scene and Sho and Tetsuro followed suit just as the Max Pharmaceuticals building was rocked by several internal explosions that brought the tower crumbling to the ground.
Over a year after the destruction of its Japan branch, Cronos established itself as the world's sole government body and built a new Japan branch in the center of Tokyo. This new branch was overseen by the Zoalord Friedrich von Purgstall.
Below is a list of Zoanoid types confirmed to have been developed by Cronos Japan.