TV-Series
Description
Kōichi Hoshi is the older brother of Shinichi Hoshi and a secret agent for an underground intelligence organization known as Phoenix, where he is designated Agent P77. To maintain his cover and protect his family from the dangers of his work, he presents himself publicly as a struggling manga artist. His background is marked by a personal tragedy: a close friend who previously held the P77 designation was killed by the rival espionage network Interspy, and Kōichi joined Phoenix specifically to avenge that death. This loss fuels a deep-seated drive for justice that defines his actions throughout the story.

Kōichi is athletic, brave, and highly capable, willing to risk his life for his cause. He hides his true identity even from his brother, which can make him appear unreliable or mysterious to those closest to him, but this secrecy is born from a protective instinct. His personality is defined by a strong sense of duty; he is motivated by a desire to protect the Earth from global conspiracies, environmental threats, and the machinations of corrupt governments and criminal syndicates. He approaches his missions with seriousness and resourcefulness, often operating alone or with limited backup.

In the story, Kōichi serves as a human counterpart and occasional ally to the three alien agents known as Wonder 3. While the extraterrestrials observe humanity from an outsider perspective, Kōichi represents humanity's internal struggle against its own destructive tendencies. His work frequently intersects with the activities of the Wonder 3, providing them and his brother with a grounded view of the political and criminal threats facing the world. In the final episode, when the galactic council orders Earth's destruction, Shinichi runs to Kōichi for help, leading Phoenix agents to engage the alien saucer in a failed attempt to stop it.

His key relationships are centered on his younger brother Shinichi, whom he cares for deeply despite his frequent absences. He also works alongside other Phoenix operatives such as the agent Elise. His primary adversary is Interspy, though he fights a range of enemies in his line of work. He maintains a protective but distant relationship with the Wonder 3, who are unaware of his true nature for much of the series, though their paths cross during his missions.

Over the course of the series, Kōichi's arc highlights the theme of unsung heroism: a lone man striving to save a world that is largely unaware of the existential dangers it faces. His role underscores the tension between covert action and open cooperation, as he must balance his secret duties with his responsibilities as a brother.

Notable abilities include strong martial arts skills, which he relies on more often than firearms. He occasionally uses guns, but his primary tools are a multipurpose watch and a pipe. The watch contains a small hammer and chain for close combat, a radar for tracking enemies and targets, and a flashlight that can also emit a blinding beam to disorient opponents. His pipe is equipped with a smoke gas that allows him to conceal his movements and escape from dangerous situations. These gadgets, combined with his physical training and tactical intelligence, make him an effective field agent.