Eternity Larva is a kindhearted swallowtail butterfly fairy. However, she occasionally says and does things that suggest she couldn't possibly be a fairy, including the use of her overly powerful ability. Okina once said she may well be the God of Eternal Night. Whatever the case, there are more than a few mysteries surrounding Eternity Larva's existence.

Wriggle Nightbug is a firefly youkai in command of countless insects. She looks like an ordinary young girl with a slightly tomboyish appearance. However, many of the insects under her control look absolutely terrifying, with some being highly venomous. Whatever the case, you'd be wise not to underestimate Wriggle.

The God of Eternal Night is written about in the Chronicles of Japan, which depicts them as a giver of prosperity and long life. The God of Eternal Night once had followers all across the land, but with worshippers not receiving their promised prosperity, they soon became the target of much hatred. From there, the God of Eternal Night stopped being worshipped altogether and faded into the shadows of history. According to one theory, they took on the form of a swallowtail butterfly larva.

Swallowtail butterflies are active during the day, while fireflies come out at night. With Eternal Larva being a swallowtail butterfly fairy and Wriggle being a firefly youkai, the two never cross paths. Under normal circumstances, that is. The sun was setting on the mountain as another day was coming to a close. All of a sudden, their eyes met, if only for an instant.

The flowers blushed in shades of deep red as the sun inched lower. Among them danced a fairy and a youkai. The fairy smiled brightly as the youkai stretched a hand out toward her. She opened her lips to speak, but a soft gust of wind kept the words from the youkai's ear. Did the fairy say what the youkai wanted to hear? Only the flowers at their feet will ever know for sure.