Eridanus is a constellation in the southern hemisphere. It is represented as a river; its name is a Latin name for the Po River and also the name of a minor river in Athens. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations. It is the sixth largest of the modern constellations.
The Eridanus Saint is one one several unnamed Saints of unrevealed rank appear briefly only in the anime adaptation, forming part of Athena’s army led by Sagittarius Sisyphos in the attack to Hades’ castle.