The character known as Guyver II is the armored alter ego of Oswald A. Lisker, also referred to as Risker in some sources. Before his transformation, Lisker served as an inspector for the global organization known as Chronos. His duties were broad, involving the monitoring of regional branch progress and the oversight of critical item transportation. He was dispatched to the Japan branch with a specific mission to supervise the transfer of three inactive Guyver units. Upon arriving, he expressed significant frustration upon learning that the branch director, Genzo Makishima, had lost these units. After one of the units was recovered in a damaged state, Lisker insisted on a personal inspection. During this process, the damaged unit spontaneously activated and forcibly bonded with him, making him the host for the second Guyver unit. Prior to this event, Lisker was being trained for conversion into a Hyper-Zoanoid, a process that had equipped him with extensive martial arts and military combat skills.

In terms of personality, Lisker is characterized by pronounced arrogance, a strong sense of vanity regarding his appearance and fighting prowess, and a condescending attitude toward those he considers subordinates, such as Genzo Makishima. These traits intensified after bonding with the Guyver unit, amplifying his self-assurance and exposing sadistic tendencies. His primary motivation as Guyver II is to retrieve the remaining Guyver units for Chronos and eliminate the rival hosts, specifically Sho Fukamachi, the host of Guyver I. His ambition is driven by a desire to ascend Chronos' hierarchy, emboldened by the power he now wields. He demonstrates a strong confidence in his own superiority, believing his combat experience makes him a more effective warrior than the untested Sho.

Lisker’s role in the story is that of a formidable antagonist. After his transformation, he assumes command of the operation to retrieve the missing units and organizes a direct attack on Sho Fukamachi’s high school. He engages Sho in combat, leveraging his superior training to initially gain a decisive advantage. His key relationship is his rivalry with Sho Fukamachi, whom he views as an obstacle to be eliminated. This rivalry is central to his narrative arc, as his overconfidence and the flawed nature of his own unit ultimately lead to his downfall.

The development of Lisker is tragic and directly tied to the defective nature of his Guyver unit. Despite his lethality and tactical precision, the physical damage his unit sustained before bonding proves fatal. The control medal, the core component that regulates the symbiotic relationship between the armor and the host, has a critical dent. This damage causes debilitating malfunctions during crucial moments in his battles. During his final confrontation with Guyver I, another malfunction allows Sho to land a blow that dislodges the damaged control medal. Without the medal to regulate the bio-organism, the Guyver unit consumes Lisker alive, and Sho ends his suffering by vaporizing him with the Mega Smasher.

Notable abilities are derived from the standard Guyver arsenal, which Lisker wields with deadly proficiency due to his prior training. In his armored form, he stands approximately 210 centimeters tall and possesses superhuman strength, speed, and durability. His weapon systems include the Head Beam, a multi-directional laser mounted on the forehead that utilizes excess body heat. He can extend High-Frequency Vibration Swords, also known as Sonic Swords, from his forearms; these blades vibrate at an extremely high frequency to cut through almost any material. His most powerful weapon is the Mega-Smasher, two high-power particle cannons contained beneath his chest armor. He also has access to a Gravity Control Orb, which allows for flight and can unleash destructive gravity waves in the form of a Pressure Cannon. Despite having access to this powerful arsenal, his effectiveness is critically undermined by the instability of his damaged control medal.