Will-o'-the-Wisps and the May Queen. Book 1. Ghost Lights

When the will-o'-the-wisps appear in the Borderland on a May night, celestial maidens come from the Heavenly World of Deities. Pure Ones, created by the Deities themselves, and dark Demons fight for the right to possess them. For on whose side the celestial maiden is, victory will come to that side. The girl Eru has very active and successful parents in life. She has a very successful younger sister, who at the age of twenty-five has already managed to start her own business, get married, have a child, and also manages to combine parenthood with work.
Eru herself has neither a permanent job nor a personal life. She lives with her parents and is often overcome by very dark thoughts.
One day, the girl saw a strange dream. It was as if will-o'-the-wisps descended from the ceiling towards her. Let's remember the story her mother once told her: Eru follows the will-o'-the-wisps through the blue fog. And she comes out to an amazing place in which there are two sanctuaries with columns. In each sanctuary there is a group of beautiful people who begin to call the girl to them.
By the will of fate, Eru, without knowing it, goes to those who call themselves 'Pure Ones'. And without realizing it, she unwittingly enters into a contract with the King of the Pure Ones, Erian...
The Pure Ones call Eru 'the celestial maiden' and worship her like a goddess. And she doesn't yet know that the 'sacred marks' (similar to social network accounts) that she sees next to the Pure Ones, if she looks at them for three or more seconds, will cause her a lot of pain. For 'sacred marks' reveal information about their owners that Eru would prefer never to know...
But it's just a dream, isn't it? Or... Is this not a dream after all?
Meanwhile, no one yet knows that the Sky Tower, which is visible in the sky, keeps its own special secrets, which neither the Pure Ones nor the Demons know about...