Enzyme is a special breed of Zoanoid designed for a specific purpose: destroying the symbiotic alien armour known as the Guyver. Following repeated failures to capture the Guyver, Richard Guyot - commander of Cronos Japan - ordered the development of a new type of Zoanoid designed specifically for killing the Guyver, and used the Japan branch's former head Genzo Makishima as a guinea pig. The development was incomplete, but successful. The first Enzyme model succeeded in killing the Guyver 1 and removed its control medal. However, Guyver 1 was resurrected by the control medal, which used traces of Sho Fukamachi's DNA left on it to regenerate his body. With the threat of the Guyver increased and the destruction of its Japanese branch, Cronos renewed the development of the Guyver-Killer class and created new Enzyme samples to combat the Guyver.
Enzyme IThe original model of Enzyme developed at Cronos Japan. Genzo Makishima had repeatedly failed to retrieve the Guyver units and so he paid the penalty by forcibly undergoing Zoanoid optimization. The result was this huge, gruesome monster. While Enzyme I is large and cumbersome, it possesses high endurance and can take a lot of punishment. When it fought Sho Fukamachi - Guyver I - it sustained a laser wound to the chest, a severed arm and even lost half its head, yet was still able to fight and win. Its main weapon against the Guyver was its blood, which possessed a potent enzyme that attacked the cells of the bio-boosted armour, swiftly dissolving it. Its blood would lose potency if it came into direct contact with the air and so Enzyme's body was optimized with numerous transfusers to transport its blood effectively. Its claws, teeth and tail barb could all pass on its blood through direct contact with the Guyver. Guyver I was unable to fight Enzyme at close range due to the creature's blood melting its armour and even lost one of its vibro-swords by slicing off Enzyme's arm. Enzyme managed to cripple the Guyver and remove his control medal, causing the armour to overload and eat its host alive. However, the Guyver remained active after a partial degeneration and attacked Enzyme again. Commander Guyot telepathically ordered Enzyme to self-destruct, causing its body to explode and spray what was left of the Guyver with its corrosive blood. Both the Guyver and Enzyme collapsed into a pile of molten flesh, which quickly dissolved completely.
Enzyme IIThe second version of Enzyme was developed at Cronos's Mount Minikami base by the organisation's co-founder, Dr. Hamilcar Barcas. With the original Enzyme data lost along with Cronos Japan, this new model had to be developed from scratch. The original test subject for Enzyme II was Fumio Fukamachi, Sho Fukamachi's father.
Enzyme II, like its predecessor, had a large body and possessed superior physical strength. It was also more agile than the original, its dexterity enhanced with the addition of four multi-jointed limbs extending from its back, offering it increased attack range and the ability to cling to different surfaces. The enzyme in its blood could be passed through its claws and its scythe-like feelers, and since it had been enhanced to the point where it no longer oxydized upon air contact, it could also be expelled from the creature's mouth in thick streams.
When Cronos abducted Fumio Fukamachi - the father of Guyver I - they used him as the first Enzyme II test subject. When Sho later rescued his father from Mt. Minikami, Dr. Barcas used his Zoalord telepathy to command Fumio to attack his son. Fumio transformed and father and son fought, but Sho was hesitant to use the Guyver's weapons and could not protect himself against Enzyme II's assault. Enzyme II managed to rip out a portion of Sho's brain, causing him to lose consciousness and activating the Guyver's self-defence mode. Without its host guiding it, the Guyver mercilessly attacked the transformed Fumio and obliterated him with the Mega-Smasher. For a time after regenerating from his wounds, Sho was unable to bio-boost again due to the trauma of killing his own father. He would later be able to reactivate the Guyver, but Cronos would also continue producing Enzyme units.
Enzyme IIIThe latest and most powerful version of the Guyver-Killer-type Zoanoids. Enzyme III is a much sleeker version than the previous two models and can also fly thanks to wings on his back; the wings can be deployed, or folded away as needed. Unlike Enzyme II, this model cannot spray its deadly enzyme, instead relying on its claws and a long, prehensile, stinger-tipped tail.
This model also has the ability to specifically fight Aptom; these Zoanoids cannot be absorbed by him thanks to a special virus with which they have been infected.
They heal from almost any injury in seconds and can even reattach severed limbs without loss of function.
Their great power and versatility come at a cost: their metabolism has been boosted enormously, which means they have to be kept in regeneration tanks when inactive, and even so their projected life span is only about three years.
They also lack any individual personality or intelligence. All they are capable of, or capable of thinking of, is killing. They cannot distinguish between ally or enemy unless they are directly controlled by a Zoalord - another reason to keep them in regeneration tanks until deployed.
Enzyme III has made no animated appearance and has only been seen in the Guyver comic series.