The Cepheus Coin (a Constellation Coin in Endless Ocean: Blue World) is one of the six coins needed to complete the Voice of the Night Sky quest The Hero Perseus. It can be found in the Zahhab Region, at coordinates D-8, among several green funnel-shaped corals. In the zoom-mode spot, the player can also find a pair of Southern Orange-Lined Cardinalfish.
- The constellation Cepheus depicts Cepheus, King of Aethiopia. Cepheus was married to Cassiopeia and fathered Andromeda, who are also constellations in the night sky.
- Cepheus is depicted in artwork as holding his arms up to the sky, pleading with the gods to spare his daughter the fate of death via being devoured by the sea monster Cetus. Eventually, Andromeda was saved by the hero Perseus.