OVA
Description
Reo Shishiou (also romanized Leo Shishio) served as Chief Scientist of the Gutsy Geoid Guard (later Gutsy Galaxy Guard), bearing primary responsibility for all G-Stone-related technologies. He is the father of Guy Shishioh, uncle to Renais Kerdif-Shishioh, and brother to Liger Shishiou.

After Guy suffered a near-fatal encounter with EI-01 in space, Reo designed the cybernetic body that saved his son's life. To bypass legal restrictions for this experimental procedure, Reo formally declared Guy legally dead and staged a public burial. This enabled him to utilize Guy's G-Stone as a life support system. Reo maintained a flippant outward demeanor regarding Guy's combat role in GGG, though his underlying paternal concern manifested in a strict condition: Guy could only participate in battles at Reo's explicit request.

Despite being 70 years old, Reo displayed notable vitality, frequently navigating the GGG Main Order Room using jet-powered roller skates ("Jet-Rollers"). This mobility method facilitated his "Reo Lariat" attack, accelerating towards targets—often his brother Liger—and striking them with his elbow. He also participated in field operations, notably manually piloting LinerGao through the Final Fusion sequence against EI-15 and remaining aboard during GaoGaiGar's subsequent fight.

Reo met his end during GGG's final confrontation with the 31 Machine Primevals in Jupiter's orbit. Piloting the Assault Reconnaissance Cutter Murakumo, his vessel was destroyed and fell into Jupiter's gravity well. His spirit was preserved by "The Power" generated by Jupiter, merging with the planetary energy. Within Jupiter, he reunited with his deceased wife, Kizuna Shishiou, who had undergone a similar transcendence. Together, they channeled vast amounts of "The Power" to aid the Mobile Unit in destroying the remaining Primevals.

A photograph in the seventh episode of *King of Braves GaoGaiGar FINAL*, showing Reo and Kizuna with Jupiter in the background, symbolically confirmed his continued existence in spirit form within the planet.