Nice is a high-ranking hero who serves as the original holder of the number ten hero ranking in the world of To Be Hero X. Known as the Perfect Hero, he is a manifestation of the ideal hero as imagined by the public, fighting with the elegance of a ballerino and mesmerizing all who witness his battles. He is a major figure who appears across multiple arcs of the story, sometimes in a minor yet pivotal capacity and at other times in an antagonistic role. His public image is one of flawless perfection, but this contrasts sharply with his private struggles and inner turmoil. He is defined by deep loyalty, a strong sense of duty, and a willingness to sacrifice himself for his convictions, often acting without expectation of recognition or reward. His backstory is hinted at throughout the series but is not fully explored, and his character is ultimately treated as a tragic figure whose emotional qualities are used more for shock or atmosphere than for personal growth. He embodies the idea of the perfect hero as a construct shaped by public belief, and his story underscores the weight and isolation that can accompany such an image.

Lin Ling is a civilian who works as a staff member at the company responsible for producing commercials for Nice and Moon, and he is frequently overworked by his employers with little time off. After witnessing Nice's death, which is reported as a suicide, he is forced by his employers to assume the hero's identity and take his place. He becomes the protagonist of the first major story arc and appears as a minor character in later arcs as well. As Nice's replacement, Lin Ling is an ordinary person thrust into an extraordinary role he never asked for, and his journey revolves around the pressure, danger, and moral complexity of pretending to be a hero he is not. His motivations stem from external compulsion rather than personal ambition, making him a reluctant figure caught in a system that treats heroes as products. In physical appearance, Lin Ling is a young man in his early twenties with brown hair marked by a white streak and brown eyes. His development is tied to his struggle to navigate the expectations and dangers of the hero industry while maintaining his own identity beneath the borrowed mask.