Hiro is the protagonist of the story, a man who finds himself transported from his ordinary life on Earth into the vast and dangerous expanse of a space-faring future. In his previous life, he was known as Satou Takahiro, a twenty-seven-year-old network administrator living in Hokkaido, Japan. After completing technical college, he worked for a local firm where, despite a lack of formal expertise, he was put in charge of network security. This job was a constant source of frustration, as he spent much of his time dealing with computer viruses that his coworkers would inadvertently introduce from various corners of the internet. His social life was limited, in part because others found his appearance, specifically his eyes, to be intimidating. He was single and his main hobby was playing video games, a pursuit he dedicated himself to with great focus, regularly achieving top scores in national rankings without ever claiming first place. He was particularly drawn to a space-faring game called Stella Online, which let him explore the cosmos on his own terms.

In terms of personality, Hiro possesses a complex mix of traits that drive his actions. He is fundamentally a benevolent person, treating his crew with genuine care and generosity, but he is also a pragmatic professional who shows no mercy to his enemies, like space pirates, often eliminating them without hesitation. He is a self-professed adrenaline junkie who feels most alive when deep in the heat of a space battle, a tendency that has earned him the nickname psycho from some military officials who witness his daring and unorthodox tactics. While he frequently claims to be a mercenary only interested in money, he struggles to ignore the plight of others, often going out of his way to rescue those in need, an impulse that has led to him taking on several crew members. He is also a self-admitted chivalrous pervert who enjoys the company of attractive women but is not predatory, and he often finds himself in unexpected intimate situations due to local customs he does not initially understand. His past as a social outsider in Japan also left its mark, and he can be socially awkward regarding the norms of his new universe.

Hiro’s primary motivation is surprisingly simple and grounded. His main goal is to earn enough money as a mercenary to purchase a detached house with a garden, a peaceful and stable home that contrasts sharply with his former life. He also has a deep desire for simple, real food and, most notably, for carbonated drinks. He is not driven by a desire to return to his old world, as he quickly adapts to and begins to enjoy his new reality. He wants to live freely as a mercenary without being tied down by the military or the political structures of the Empire, even as he finds himself repeatedly drawn into major events.

Within the story, Hiro serves as the captain of his powerful starship, the Krishna, and the leader of a growing crew. He is an agent of chaos and change within the established order, using his unprecedented skills and out-of-context knowledge from his gaming days to upend battles and affect the political landscape, much to the bewilderment of authorities. His role is that of the experienced protagonist who, despite being new to the physical realities of space combat, has years of virtual experience to draw upon.

Hiro's key relationships form the core of his new life. His first and closest crew member is Mimi, a young woman he rescues from a desperate situation. He not only saves her but also pays off her deceased family's debt, offering her a place on his ship, where she becomes his ship operator and lover. Another critical relationship is with Elma, an experienced space elf mercenary who first helps him navigate the bureaucracy of the Mercenaries Guild. After her own ship is destroyed, Hiro buys her crushing debt, and she joins his crew, becoming another intimate partner and a valuable advisor. He also has a complex relationship with Serena Holz, a noble and military officer who recognizes his talents and repeatedly hires him for dangerous missions, often to his own reluctant consternation.

Hiro undergoes subtle but important development throughout the series. He begins by still harboring the lingering sensation that his new reality is just a game, which allows him to remain strangely calm in life-threatening situations. Over time, he learns the harsh and real consequences of his new universe. He also evolves from a lone operator into a responsible captain, learning to manage and care for a crew. Perhaps most significantly, he slowly uncovers and begins to develop his own latent psychic abilities, which he initially had no knowledge of and must learn to control.

Hiro's notable abilities are overwhelmingly focused on combat and piloting. He is an ace pilot of the highest order, capable of performing impossible maneuvers due to the thousands of hours logged in his video game. His piloting skill is such that when the Mercenaries Guild tested him, his raw ability was immediately placed at the gold rank, one step below the highest, despite his lack of real-world accomplishments. He is a combat pragmatist who uses clever tactics, like hiding in a larger ship's blind spot or using stealth to ambush enemies. He has an intuitive form of combat clairvoyance, allowing him to sense an opponent's killing intent and know where to dodge before a shot is fired. He is also an instant expert, able to pick up new skills, such as melee combat, with startling speed under the right instruction. All of this is augmented by his powerful and heavily customized ship, the Krishna, which is an ace custom light fighter armed with hidden high-power pulse cannons and military-grade armor.