Zerbebuth was developed by the Chronos Corporation as an early model of Hyper-Zoanoid using the highest level of the organization's genetic optimization techniques. He is a one-of-a-kind model like most Hyper-Zoanoids and apparently has a long-standing rivalry with Cronos inspector Oswald A. Lisker - the host of Guyver-2 - whom Zerbebuth had trained with before he underwent Zoanoid processing.
Manga and OVA
In the Guyver manga and OVA, Zerbebuth was dispatched to kidnap Sho Fukamachi's (Guyver-1) girlfriend, Mizuki Segawa. Luring the Guyver into an abandoned warehouse, Zerbebuth dispatched a group of Zoanoids to attack Sho, expecting them to fail but knowing that Sho would exhaust himself fighting them, making it easier to kill off the Guyver himself. When he fought Sho, Zerbebuth was unaffected by Sho's punches and head-laser. Sho managed to distract Zerbebuth, however, by lasering a rafter down on top of the Zoanoid, then kneeing him in the face. The impact cracked Zerbebuth's skull and he fell back in order to use Mizuki as a shield. He found that the Chronos grunts guarding Mizuki were dead, slain by a dark figure who appeared to be another Guyver. Guyver-3 sliced Zerbebuth in half with his vibro-blades.
In the 2005 Guyver TV series, Zerbebuth accompanied Commander Guyot to Chronos Japan along with a squad of three other Hyper-Zoanoids. He was dispatched to attack the Guyver outside Sho's school and nearly succeeded in killing him, but was distracted by the arrival of a local cop. Deciding he needed to silence any witnesses, Zerbebuth killed the officer with his acid spray. Angered by the murder of an innocent man, Sho tapped into the Guyver's gravity-control orb and used his Pressure Cannon attack, which was poorly aimed but managed to destroy a chunk of Zerbebuth's shoulder. Critically injured, Zerbebuth retreated to Chronos Japan for regeneration.
He would appear again after the death and subsequent revival of Guyver-1, re-optimized and enhanced with new abilities. These would not be enough to stop the Guyver, which was at that time unrestrained by Sho's consciousness. Zerbebuth was left crippled and dying until he was found by Lisker (Guyver-2). Lisker used his Sonic-Buster to put Zerbebuth out of his misery.