Jinto Lin, originally named Jinto Linn, is introduced as the son of the president of the planet Martine. His entire life is upended when the space-dwelling Abh Empire arrives to annex his home system. To prevent bloodshed, his father surrenders the planet and negotiates a position within Abh society for himself and his family. As a result, a young Jinto is granted the title of Count of the Hyde system, becoming an Abh noble despite being a "Lander," a person born on a planet, without their genetic modifications. This political act makes him a traitor in the eyes of many other Landers, forcing him to live among the very people who conquered his world. He is sent away to be educated in Abh customs and schools, setting him on a path far removed from the ordinary life he might have led.

Personality-wise, Jinto is characterized by his thoughtful, shy, and conciliatory nature. He is a studious and methodical planner, a sharp mind who prefers to carefully weigh pros and cons rather than rely on sudden, brilliant insights. This often makes him appear as a calming and sensible presence. He is polite to a fault and typically avoids confrontation, tending to stick up for others before himself. While he can be firm and confrontational when absolutely necessary, he much prefers resolutions that do not involve shouting or conflict. Jinto is deeply aware of his unusual position as a human who has been adopted into a race of genetically engineered space-dwellers. He struggles with a classic immigrant's dilemma, constantly negotiating his identity between his original heritage as a Lander from Martine and his new, legally defined role as an Abh noble. He often feels like an outsider, sensitive to accusations of being a traitor to his own kind, even as he begins to believe in the rightness of the Abh cause. This internal conflict is a core part of his character, and he often finds comfort in routine and close relationships.

Jintos primary motivation throughout the story is his profound sense of loyalty and his need to find his place in the universe. Having lost his home and his previous identity, he clings to the connections he forms. Most significantly, he feels an overwhelming need to remain by the side of Lafiel, the Abh princess he meets on his journey to military school. Their relationship is the emotional core of his journey. He is often her voice of reason, reining in her more violent or glory-seeking impulses, while she in turn helps him to overcome his paralyzing self-doubt. The nature of their bond is complex and deep, moving beyond simple friendship, though both characters are nervous and awkward when confronting the romantic implications. Jinto is also acutely aware of the tragic disparity in their lifespans, knowing that he will age and die while she remains youthful for centuries, a fact he struggles with internally.

In the story, Jinto serves as a vital point of view character, offering a grounded, human perspective on the vast interstellar war and the alien culture of the Abh. After completing his mandatory education and training, he serves as a supply officer and secretary aboard the assault ship Basroil, under the command of Captain Lafiel. His role is primarily logistical, monitoring fuel and ammunition levels during battle and managing supplies, a job that suits his methodical and detail-oriented nature. In this capacity, he is a key member of a small, tight-knit crew, and his administrative skills are essential to the ship's operations. Over time, he grows from a nervous, somewhat passive young man into a more self-assured and frank officer. By the events of Banner of the Stars, which takes place three years after his initial meeting with Lafiel, he has become more confident in his duties and more direct in his interactions, though he remains ever-cognizant of his unique status. His development is marked by a gradual acceptance of his hybrid identity and a growing willingness to act on his own convictions.

Jinto possesses no superhuman abilities. He is an ordinary human who must follow a strict exercise regimen to prevent physical deterioration during long space voyages. He has received standard military training, including instruction with a laser pistol, but his true competence lies in his non-combat skills. As a supply officer, his abilities are those of a highly efficient clerk, quartermaster, and certified accountant. He is also trained in basic starship systems maintenance and repairs. His sharp memory, methodical thinking, and ability to improvise under pressure are his greatest assets, making him far more capable than his "milquetoast" exterior might suggest.