Subaru

Subaru is a Steel Saint in Omega Era. He seems to have an unmastered Cosmo.

Personality
Fearless, he loves fighting, although he is immature and not well suited for teamwork.

Background
Subaru is one of the Steel Saints Mitsumasa Kido's technologically enhanced special backup unit for Athena's Saints, created decades ago.

Encountering Kōga
Subaru meets Koga and challenges him to fight against, envies Subaru that Kōga  killed the God of Darkness Abzu. When Subaru is challenging Kōga comes a Pallasite called Tarvos. Subaru puts his Steel Cloth  and starts fighting with Tarvos but this is very strong and subaru is defeated.

In episodes it shows he has red eyes flashing just like Hades power like flowing in him or something and during episode 58 it shows that he never Athena got like a feeling that he like he meet Athena before.

Travel to Palaestra
After deciding to go with Koga and then defeat, reaching the shrine, there are with Shaina, enter in a short battle in which surprises his opponent for his cosmo. Moments later at Palaestra meet Sōma and together they go where they are Geki and the other Saints of Steel in entrenamient.Mas later joins the fight against Loge and his bees, dedicating this to repel, in combat need a change of Steel Cloth.

In Astronomy
The Pleiades (/ˈplaɪ.ədiːz/ or /ˈpliː.ədiːz/), or Seven Sisters (Messier object 45 or M45), is an open star cluster containing middle-aged hot B-type stars located in the constellation of Taurus. It is among the nearest star clusters to Earth and is the cluster most obvious to the naked eye in the night sky. The name Pleiades comes from Greek mythology; the celestial entity has several meanings in different cultures and traditions.

In Mythology
The Pleiades (/ˈplaɪ.ədiːz/ or /ˈpliːədiːz/; Ancient Greek: Πλειάδες [pleːádes], Modern [pliˈaðes]), companions of Artemis, were the seven daughters of the titan Atlas and the sea-nymph Pleione born on Mount Cyllene. They are the sisters of Calypso, Hyas, the Hyades, and the Hesperides. The Pleiades were nymphs in the train of Artemis, and together with the seven Hyades were called the Atlantides, Dodonides, or Nysiades, nursemaids and teachers to the infant Bacchus.

Trivia

 * Subaru's Steel Cloth is reminiscent of the appearance of the character Megaman from the Megaman Metaseries of games and media. note the upper red crystal piece upon his helmet, as well as the general color scheme, and mechanical nature of the steel cloth itself.