Seiya is one of the eighty-eight Saints, mythical warriors who have served the goddess Athena and protected Earth throughout the ages, though he is initially only interested in finding his missing sister, Seika.

Like most of Kurumada's characters, Seiya's design was inspired by Ryuji Takane, the protagonist of his manga Ring ni Kakero.

[4] Along with Hyoga's Cygnus, Pegasus was chosen as Seiya's constellation from the beginning, with the series later expanding on the twelve signs of the zodiac.

[5] Seiya's likeness was inspired by Ryuji Takane, the protagonist of Kurumada's manga Ring ni Kakero, which he considers to be his favorite creation.

[7] Furuya stated that Seiya was his favorite character out of all his voice roles and laughed when performing his "Pegasus Meteor Fist".

Seiya draws his superhuman powers from the Cosmos, the energy of the Big Bang that is present in all living things and connects a Saint to his constellation and Cloth.

[17] After mastering the Cosmos known as Seventh Sense, Seiya and his friends defeat the strongest Gold Saints, including the Pope, who is revealed to be Gemini Saga, and save Saori.

[18] Following the battle against Saga, Saori confronts Poseidon's reincarnation, Julian Solo, who seeks to flood the world, and attempts to sacrifice herself to stop him.

While reaching Poseidon, Seiya occasionally wears the Gold Cloth of Sagittarius, whose true owner, Aiolos, died thirteen years prior to the events of the series.

[21] In the Hades arc, Seiya returns to the Sanctuary to talk to Marin, but instead finds Aries Mu being attacked by the undead Cancer Death Mask and Pisces Aphrodite.

[22] In the Underworld, Seiya and Shun meet the missing Silver Saint Lyra Orphée, who plans to kill Hades by attacking him with the Judges.

[23] Using the wings, Seiya arrives in Elysion, where he encounters the God of Death, Thanatos, who he and his friends struggle to defeat even with the Gold Cloths.

However, when Seiya learns that Saori has found Seika, his Cosmos causes the destroyed Bronze to transform into a God Cloth and reach Thanatos' level.

To save him, Athena Saori Kido, Andromeda Shun, Phoenix Ikki, Dragon Shiryu, and Cygnus Hyoga travel to the past to remove Hades' sword before it can strike Seiya' heart.

It was explained in the Japanese DVD audio commentary with director Shigeyasu Yamauchi that, since Seiya and Saori's greatest strength was their love and trust for each other, Apollo erased their memories so that they would not regain the will to rebel against the gods.

Seiya is shocked to learn that his current enemy is his father Mitsumasa Kido, reborn as a divine being, and that the gods have killed Athena.

[34] Near the end of season 1, Seiya returns to help the Bronze Saints stop the God of Darkness Abzu from manipulating Koga, who he lends his Sagittarius Cloth.

[42] Anime News Network comments that Seiya's voice actor for the English dub is unsuitable, that he enunciates strange words, and does not sound heroic.

Additionally, Thompson noted that Seiya's speech in the series' last arc regarding how he blames gods for humanity's problems is similar to "atheism or anti-theism", comparing him with the 2010 film Clash of the Titans.

[45] Mark Thomas of the Fandom Post criticized Seiya's overuse of his Meteor Fist, even when his enemies manage to block it.

[46] In a review of Legend of Sanctuary, Screen praised Seiya's comical characterization and the performance of the Pegasus Meteor Fist technique.

[48] In "Blood, Biceps, and Beautiful Eyes: Cultural Representations of Masculinity in Masami Kurumada's Saint Seiya", author Lorna Piatti-Farnell notes that the masculinity Seiya, Shun, Hyoga and Shiryu bow to involves accomplishments of their goals of justice might not come as a surprise, as the magazine Shonen Jump often has manga that involves this predicaments.

[51] The Daily Dot criticized the friendship Seiya develops with his friends, as they form a bond despite knowing each other for only four episodes in the Netflix series.

[52] In "Las funciones del Leitmotiv musical como componente narrativo de los géneros de animación japonesa Shonen y Seinen", Carlos Manuel and Yache Vigo from Universidad Privada del Norte described Seiya as a character distinguished by his bravery and his passion, which is easily notable when his leitmotif starts playing in the series.

They are fighting for the Gold Cloth rather than justice, which would become the center of another conflict when the renegade Phoenix Ikki and the Black Saints come to Japan to steal it.