Gresvan (그레스반) was a planet that was destroyed nearly a thousand years ago.
About a thousand years ago (in the year D0), humans swore that they would only borrow the gods' powers for their magic and renounced the suras. Gresvan became one of the planets that was destroyed in retaliation.
In the year D1, Gandharva was sighted near this planet by the god Varuna. The image of Gandharva in his sura form is a reconstruction based on that encounter. Gandharva eventually destroyed Gresvan.
Chandra states in the main story that Gandharva's destruction of Gresvan was petty because the humans chose divine magic over fiendish magic. 100 million souls were destroyed in such a way that they were unable to go to the afterlife. Chandra also implies that the destruction of each planet shortens the lifespan of the universe.