Jinpei, codenamed G-4 and dubbed the Swallow, operates as the Science Ninja Team’s youngest member, excelling in reconnaissance and stealth. Estimated between 10-11 years old, his origins are shrouded in mystery. Rescued as a toddler by Jun in the Jupiter Mountains during her wartime escape, the pair were raised at Shirayuki Orphanage under Dr. Nambu’s guardianship before joining his elite squad. Jinpei asserts lineage from the 18th-generation Iga Ninja clan, hinting at ties to the Jupiter Ninja Clan’s missing sensei—a thread left unresolved. Boasting a lively, mischievous demeanor, Jinpei tempers his prankster tendencies with dedication, aiding Jun in operating Snack J between missions. Though he partners with Ryu for comedic antics as the team’s “idea man,” his strategic instincts surface during high-stakes operations. Relationships pivot on familial bonds: he shares a playful, sibling-like dynamic with Jun, often ribbing her over her affection for Ken, while deferring to Ken as “Aniki” (big brother) in acknowledgment of his leadership. Jinpei’s toolkit adapts across eras. The original series arms him with American Clackers (bolas), later upgraded to the Rebound Ball in *Gatchaman II*. *Gatchaman Fighter* introduces the Swallow Top, a spinning top-yo-yo hybrid. The 1994 OVA reimagines him as a tech-savvy infiltrator, hacking Galactor systems via a collapsible device linked to his helmet visor. His Bird Style uniform shifts from classic yellow with red accents and a teal-lined cape to an OVA redesign of red with yellow highlights and a purple cape. His vehicles mirror mission demands: the Swallow Helico VTOL aircraft handles covert insertions, while the *Gatchaman Fighter*-era Gatcha Four tank merges into the Gatcha Spartan mecha. The OVA swaps these for a magenta-and-white dune buggy equipped with flight tech. Spin-offs such as *Yatterman* and *Time Bokan: Royal Revival* place him in background cameos, often silent or crowd-blended. Evolution across sequels reinforces his role: *Gatchaman II* streamlines his arsenal with the Rebound Ball, while the OVA sharpens his hacker prowess to match 1990s tech trends. Though his ninja heritage remains underexplored, his unwavering loyalty and combat versatility anchor his presence through every iteration.