Jason, designated G-2, is the second-in-command and a core member of the international science ninja team. His civilian identity is that of a professional race car driver, a solitary pursuit that matches his independent nature. In the original Japanese version, his name is Joe Asakura, and his background is marked by tragedy: his parents were members of the terrorist organization Galactor who were killed when they attempted to defect, leaving him an orphan who was then secretly taken in and trained by the team’s mentor, Dr. Nambu.

Personality-wise, Jason is characterized by a headstrong and impulsive demeanor. He is action-oriented, often preferring to engage an enemy directly with force rather than through negotiation or elaborate strategy. This makes him quick to launch an attack at the first sign of a threat. On the surface, he appears cynical, intense, and somewhat of a loner, living by himself in a camping trailer when not on missions. However, beneath this tough exterior lies a deep-seated loyalty to his teammates. Despite frequent clashes, particularly with the team leader, he holds a genuine affection for the group and a steadfast commitment to their cause. He rejects high-minded ideals but demonstrates a hard-eyed, practical brand of idealism, driven by a belief that the enemy's attacks are an outrage that must be stopped.

His primary motivation is the complete destruction of Galactor. This drive is initially fueled by the personal vendetta stemming from his parents' murder. As the series progresses, this motivation evolves into a more self-sacrificing devotion to the mission, especially after he sustains fatal brain damage from a previous confrontation. Learning he has a limited time to live, he becomes even more reckless, seeing himself as living on borrowed time and dedicating his last days to ensuring Galactor’s defeat, even if it means abandoning the team to face the enemy alone. In some later sequel series, his body is eventually rebuilt as a cyborg, making him functionally immortal but stripping him of some of his humanity, a transformation he uses to engage in even more dangerous operations.

In the team dynamic, Jason serves as the group's weapons expert and marksman. His role often puts him at odds with the more strategic and level-headed leader, Ken (known as Mark in some English versions). Their conflicts arise from differing philosophies, with Jason arguing for brute force and overwhelming firepower over careful planning. Despite these constant arguments and his outward resentment of being second-in-command, his respect for the leader is genuine. He never truly wishes to betray or take over the team, and their bickering masks a deep, reliable bond of mutual trust and friendship. His key relationships are marked by this rivalry with the leader and a protective, if gruff, camaraderie with the other members, particularly the youngest and the sole female member, Jun the Swan.

Jason possesses a notable array of abilities that make him a formidable fighter. He is an expert marksman with incredibly sharp eyesight, a skill that earned him his bird motif. His primary weapons include a multi-purpose pistol that can fire a barrage of feather-shaped shuriken, function as a cutting torch, or deploy a grappling cable. He also carries individual feather shuriken, which can be used as thrown daggers or explosives. In his Birdstyle battle uniform, which is based on a condor, his physical agility, endurance, and speed are heightened. He is capable of performing a devastating “Tornado Fighter” attack, spinning his body to create a powerful cyclone to disorient or destroy enemies. While initially depicted as a mediocre pilot, he develops into a highly competent one, showing a dedication to mastering every aspect of his role.