Ginro is one of the gatekeepers of Ishigami Village and the younger brother of Kinro. He is a young man of sixteen to eighteen years of age, with a slim build that is not very muscular, which contrasts with many other warriors in the village. He has medium-length blond hair that often covers the left side of his face and round, green eyes. His soft facial features and overall androgynous appearance allow him to convincingly pass himself off as a girl when necessary. According to the warrior Matsukaze, Ginro bears a striking resemblance to his former lord, hinting at a possible distant relation. He typically wears a blue karate gi-like uniform and carries a spear, which is later upgraded to a steel katana.

Ginro is defined by his profound cowardice, which is presented as a sincere and prominent character trait. He is easily frightened, often complains about hard work, and tends to slack off during his guard duties. His selfish and somewhat lazy nature leads him to look for ways to shirk responsibility or take the easy way out. He is easily distracted by shiny objects and the prospect of personal gain. Despite these flaws, Ginro possesses a hidden kinder side that genuinely cares for his friends and family. While he may talk about running away from danger, he has repeatedly demonstrated an ability to overcome his fear when those he cares about are in immediate peril. He can also be quite vain and enjoys showing off, particularly in front of attractive women, and has a perverted streak, often letting his imagination run wild with superficial fantasies. He is also known for his tactless and meddlesome nature, often blurting out obvious subtext or inserting himself into the romantic affairs of others.

Initially, Ginro's motivations are primarily self-serving, focusing on avoiding work, seeking comfort, and indulging his whims. This was most clearly displayed during the village tournament to decide the next chief, where he betrayed his allies to try and win the position for himself, dreaming of ordering people around and eating ramen every day. However, as the story progresses, his motivations evolve. He begins to act out of a sense of loyalty and friendship, such as when he runs into a dangerous, poison-gas-filled crater to help Senku and Chrome collect sulfur. His primary driving force becomes the protection of his brother, Kinro, and his allies in the Kingdom of Science. He is often used as comic relief, but his role in the story is significant as he frequently finds himself in high-stakes situations where his unexpected courage or unique skills become crucial to the success of a mission.

Within the Kingdom of Science, Ginro serves as a supporting member who is often reluctantly dragged into laborious tasks by Kohaku or his brother. His key relationships are central to his character development. His bond with his brother Kinro is the most important. Despite being polar opposites in personality, they share a deep, unspoken understanding and love for each other. Ginro has repeatedly refused to abandon Kinro, even when logic dictated he should, showing that his loyalty runs deeper than his fear. His relationship with Senku is that of a lazy subordinate to an exacting chief. While he is often annoyed by the hard work Senku demands, he has full faith in the scientist's abilities and trusts that Senku will find a way to revive him if he is ever petrified. Kohaku, a fellow warrior, finds his perverted nature annoying but nonetheless considers him a good friend and has come to his aid in life-threatening situations. On Treasure Island, he gains a devoted bodyguard in Matsukaze, an ancient warrior who mistakes him for his former master. This relationship gives Ginro a new sense of confidence, though he often abuses the protection it provides.

Ginro's development is marked by a gradual but consistent shift from pure self-preservation to self-sacrifice for others. While his cowardly instincts never fully disappear, he learns to act in spite of them. A pivotal moment is when he refuses to cut the bridge to the village, knowing it would sacrifice his injured brother. Later, he endures a grievous, fatal wound from the antagonist Ibara to gather critical intelligence for his friends, accepting his death as a fair price. This act of bravery forces even his critics to acknowledge his growth. He continues to be a source of humor, but his experiences establish him as a reliable, if reluctant, member of the team.

In terms of abilities, Ginro is not considered as strong a warrior as his brother Kinro. However, he possesses considerable physical stamina and endurance. He was able to match his brother's output when spinning a generator and endured a brutal barrage of attacks from the physically powerful Argo to win a match, though he was under the influence of a caffeine supplement. He has demonstrated the ability to hunt and kill large alligators with assistance. His true skill lies not in brute force but in his agility and showmanship. He is an excellent spearman, proficient in flashy flourishes and feints, and was able to perform an impressive spear dance while in disguise. His androgynous looks have proven to be a valuable asset for infiltration missions, allowing him to pose as a woman to get close to enemies. His gear includes his spear, later a katana, and he was once equipped with a chemical agent concealed in a pineapple to incapacitate foes.