TV-Series
Description
Jinpei, known as Jinpei the Swallow and designated G-4, is the youngest member of the Science Ninja Team, where he serves as the reconnaissance expert. His origins are shrouded in mystery, as he was found as an infant at the base of Mount Jupiter by his future teammate, Jun. With no knowledge of his biological parents or true birthday, Jun named him Jinpei and established the day she discovered him as his date of birth. The two grew up together in the Shirayuki Orphanage, forming an unbreakable adoptive sibling bond. It is speculated that he might be a descendant of the Jupiter Ninja Clan or the Iga Ninja clan, but this has never been confirmed and remains part of his ambiguous personal history. When Dr. Nambu sought to recruit potential members for his scientific ninja force, he was initially interested only in Jinpei due to his exceptional agility. However, Jun refused to be separated from him, and Dr. Nambu ultimately took both children under his wing for training.

In terms of personality, Jinpei is characterized by a vibrant mix of childish exuberance and surprising responsibility. He is typically cheerful, excitable, and mischievous, often serving as a source of comic relief for the team. He enjoys playing pranks and is known for his quick wit, which sometimes manifests in the form of terrible puns. Despite his youth, he is far from helpless. Jinpei possesses a shrewd and practical side, helping Jun run her snack bar, where he works as a cook, dishwasher, and waiter. A recurring internal conflict for him is his desire to be taken seriously. Because of his small stature and young age, he is often underestimated by both enemies and allies, which drives him to be reckless and sometimes run off on his own to prove that he can handle his share of the team's burdens. He has a notable soft spot for stray animals, frequently bringing home creatures like seals, baby whales, or mountain lion cubs, much to Jun's exasperation.

Jinpei’s relationships with the other members of the team define his role within the group. His strongest bond is with Jun, whom he calls Oneechan (big sister). While he relentlessly teases her, especially about her feelings for their leader Ken, she is the person he turns to for comfort and security. He looks up to Ken Washio with deep respect, addressing him as Aniki (big brother), and follows his orders without hesitation, though he also nags Ken about paying his tab at the snack bar. Jinpei shares a more playful relationship with the team's large-hearted pilot, Ryu, with whom he is often partnered for comedic moments. Throughout the series, Jinpei demonstrates a clear need for parental support, but he manages well with the family he has found in Dr. Nambu and his teammates. His character shows notable development as the series progresses, which is partly attributed to the natural aging of his voice actor, resulting in his voice deepening in later episodes and making his maturation among the most apparent of the team.

As a fighter, Jinpei specializes in stealth and incapacitation tactics, using his small size to his advantage against larger adult opponents. His arsenal has evolved across different series and adaptations. In the original Gatchaman, his primary weapons are bolos, referred to as American Crackers, which can be outfitted with blades or explosives. In Gatchaman II, he uses the Rebound Ball, a super-ball projectile thrown from a mitt attached to his hand, and in Gatchaman Fighter, he wields the Swallow Top, a spinning top attached to a string. In the 1994 OVA, his equipment is modernized to include an unnamed hacking device, reflecting a shift toward electronic warfare and information gathering. For mobility and combat support, Jinpei pilots the Swallow Helico, a small VTOL aircraft designed for reconnaissance in tight spaces, and later in Gatchaman Fighter, he commands the Gatcha Four tank, a land vehicle that combines with his teammates' mecha to form the larger Gatcha Spartan.