Pegasus Tenma, also known as Tenma of Pegasus, is the protagonist of Saint Seiya: The Lost Canvas and the Pegasus Saint of the eighteenth century. He is an orphan of Japanese ancestry who grew up in an orphanage in Italy alongside two other children, Alone and Sasha, and the three formed a bond as close as siblings. He is fifteen years old when his story begins. His exceptional talent is recognized by the Gold Saint Dohko of Libra, who takes him to the Sanctuary and trains him until he earns the Bronze Cloth of Pegasus. His Japanese appearance and name are connected to the secret of his birth, as the story later reveals that his father is Mephistopheles Yōma, a servant of Hades. As the Pegasus Saint, his soul is fated to be reborn in every era in which Athena returns to Earth, making him the predecessor of the later Pegasus Saint Seiya.

Tenma's personal story is shaped by his relationships with Alone and Sasha. After becoming a Saint, he reunites with Sasha at the Sanctuary and learns that she is Athena, the goddess whom the Saints serve. Soon afterward, Hades' forces attack the village where the three grew up, and Tenma discovers that the body inhabited by Hades is that of Alone, his closest friend and Sasha's brother. This revelation is the emotional core of his journey. His main motivation is not simply to win the war, but to save Alone's soul and to protect Sasha and the people he loves. He refuses to accept that his friend is lost forever and fights to find a way to separate Hades from Alone's body rather than resign himself to destroying it.

In terms of personality, Tenma is spirited, determined, and fiercely loyal. He is defined by an unbreakable will and an exceptional ability to ignite and manipulate his Cosmo in a remarkably short time, a skill that helped him win the Pegasus Cloth. His fighting style is built around the Pegasus techniques, most notably the Pegasus Meteor Fist, a rapid barrage of punches that crosses the distance between opponents at speeds beyond the sound barrier. As the conflict escalates, his power grows to the point where his bond with the Pegasus constellation grants him strength beyond ordinary human limits. At his peak, while wearing the Divine Cloth, he is able to unleash the Pegasus Comet Big Bang, an all-out attack that concentrates the full force of his Cosmo into a single devastating strike.

Tenma's role in the Holy War is central. He frequently fights alongside the Gold Saints and other young Saints, including his training companion Yato, and he matures from a brash newcomer into a warrior capable of confronting Hades himself. When Hades retreats to the sky castle known as the Lost Canvas, Tenma and his allies obtain the aid of Poseidon and travel there aboard an ancient ark. They fight through the fortress at great cost, and in the final confrontation the souls of the fallen Gold Saints combine their twelve Cosmos to expel Hades from Alone's body. Tenma, Sasha, and Alone then follow the soul of the deity in spiritual form, and the combined Cosmo of the three banishes Hades from the earthly plane, ending the war and freeing Alone from possession.

Through this journey, Tenma develops from an orphan boy into a mature Saint who embodies friendship and sacrifice. His bond with Alone remains the measure of his humanity: even in the face of a god, he chooses compassion and refuses to abandon the person his enemy once was. His relationship with Dohko, who recognized his potential and guided him, and his relationship with Sasha, whose love for her brother mirrors his own, reinforce the themes of loyalty and hope that define his character. In the end, Tenma is remembered as the Pegasus Saint who stood against Hades in the previous Holy War and helped bring it to a close.