Goro Hoshiwatari is the central protagonist of the anime. He is an adolescent boy who leaves his home to travel through space on a personal quest. His primary motivation is to find his missing father, Daigo Hoshiwatari, who disappeared fifteen years before the story begins during an accident involving the prototype of a revolutionary dimensional tunnel that he had created. This goal of locating his lost parent is a constant driving force throughout his journey.

Goro's career with the YAT space tour company begins not by choice, but as a form of restitution. After an accident for which he is responsible causes significant damage to a company ship, he is required to work for YAT in order to pay off the incurred costs. In his role with the company, he often performs duties such as a mechanic or janitor. His personality is typical of many adventurous heroes; he possesses a natural bravery and an innate sense of righteousness. He is frequently bossed around by Kaoru Yamamoto, the director of YAT and captain of their ship, the YAT Dove. Despite Kaoru's gruff and often demanding nature, Goro has a deep romantic interest in the captain's daughter, Katsura Tenjoin.

Throughout the series, Goro develops close bonds with the other members of the YAT crew, including the pilot Ucchi and the navigator Kanabi, a robot who displays a range of emotions. He also attracts the unwanted romantic attention of Kanea Marigold, the wealthy and strong-willed daughter of the owner of a rival space tourism conglomerate. While Goro is primarily focused on his mission to find his father and his duties at YAT, Kanea's persistent affection for him creates a recurring dynamic. In his search, Goro holds onto an old photograph, which serves as his only tangible link to his missing father.

Over the course of the narrative, Goro shows considerable dedication to his job and his personal mission, believing that remaining with the space touring company is his best opportunity to find clues about his father's whereabouts. In a notable moment of character development at the conclusion of the first story arc, he plans to continue working for YAT, believing he has not yet fully paid his debt. However, he discovers that the insurance company had long since covered the costs of the accident, meaning he had been working for free the entire time. This realization leaves him understandably frustrated, though his connection to the crew remains. His journey continues into the second series, where he and the rest of the YAT crew are transported to a distant universe and become entangled in a conflict with the villainous Emperor Ganon.

Physically, Goro is a teenager depicted with brown hair and blue eyes. His appearance is marked by his signature goggles, which he wears on his head, and fingerless gloves.