The webtoon started explaining it so I'll just continue around where it left off. Kata and the Black Dragon start to have feelings for the girl named Armanu and lust after her. They both want her so she asks them what will they giver her in return. They reply that they will give her whatever she asks for and more. She asks them to give her 7 days to choose who to be with.
The Black Dragon sends two snakes, one white and one black to ask Armanu if she decided yet. She hasn't. They give her the advice to test both Kata and the Black Dragon to see who loves her more.
She says to Kata "I want the glory of the light that you have: heavenly beauty and eternal life." It's not easy for him to give up eternal life but when he thinks about eternal life in heaven without her, decides he can give it up to live on earth with her for a finite time.
She says to the Black Dragon " I want the abundance of land and water and your wisdom". He says he cannot give her the land and the water because it's not his to give but he can give her his wisdom. Unlike other things wisdom can be shared and it is not lost in the process.
In the end she choose Kata because he gives her everything she wants. She they got together and did the deed. He was supposed to give her eternal life after that but his father Utu told him "My son, I do not allow you to abandon what I have given you. If you give up the glory of light, that is heavenly beauty and eternal life, you will never return to heave. You will be the mud race (that's what they call humans in the book) and will have hardships, suffering all the joys and sorrows and will eventually disappear. The warriors who are your alter egos (called Elyos) will also suffer the same fate."
So Kata couldn't give Armanu eternal life and she felt betrayed and went to the Black Dragon. "He did not keep his promise. I choose you and I want to receive what you give." He laughed coldly and said that when choosing one she threw the other away and she made her choice. "But I will show you proof of my love for you. I will share the wisdom you desire, the truth I know."
Kata found out Armanu went to the dragon. He was distraught and as promised he gave the tree, the true spirit of Armanu, eternal life. (He gave the tree eternal life because she's the embodiment of the tree). After he did, he lost his divine nature and fell to the ground, the land of humans. His warriors the Eloys also fell along with him as well as the sacred tree. But Armanu the girl is no where to be found, she disappeared. The only trace left was the footprints of a large bird on the mud.
Kata begs desperately for the dragon to tell him where Armanu is. The Black Dragon warns that wisdom may be poison and tells him to try to forget her. Kata still begs and the dragon relents and says she ran away from Kata and when she left the realm of the sacred tree an evil ugly flying beast snatched her. The flying beast raped her and she gave birth to his children. The dragon tells her she is in the Baekyeon Mountain, with those cannibal birds. He also informs Kata that she was already pregnant with his children as well and gave birth to them. He told him that the children who look like you are your children.
That night his father found Kata in his dream and said "My son, take the two things you gave in vain. Then you will be able to come back to heaven". Kata asks how he can do that. His father says kill what remains of her and the glory of light you gave her will be returned to you. Burn the tree that you gave eternal life to and you will get it back. You have to reap the glory of light first and then burn the tree to get eternal life after. Because that is the order you gave them. Then you and your descendants will be able to come back to heaven.
Kata still didn't want to kill Armanu but rather stay with her. When he went to the mountains after many years he finally found out that the cannibal bird has eaten Armanu leaving no trace of her. Kata kills the cannibal bird with his arrows. He finds the children of Armanu and the bird and tries to kill them but they manage to escape in the mountains.
Kata finds his own children who are beautiful and look like him and take them to the sacred tree forest. Kata believes that because the tree is still alive, Armanu will come back again since she is the manifestation of the tree. His children say they will burn the tree to give him everlasting life back and they can go back to heaven together, the kids want to go back to heaven quickly. Kata doesn't want to because he thinks burning the tree will make it so that Armanu can't come back. So he binds the children's body and soul to the tree so that they have to protect it. Plus the condition is that they have to kill what's left of the mom in the form of the cannibal children she had. They have to do that first before the burning of the tree. It's important the order. Kata says if the tree dies first no can have eternal life. Kata then blessed his descendants so that they could use all his abilities. The son later becomes known as Altir, the guardian of the forest and his offspring become the priests of the Golden Forest
As time goes by Kata got tired of waiting. His subordinates began to die and become stones with light buried into the ground. Kata looked up to the sky, his father and prayed for the last time. "My Father Utu, All I want to do is go back to the sky. It's not about restoring dazzling glory. May I be reborn with her in the distant future, meet her again, choose her again and live with her even a lifetime. It's good to be one of the mud races that disappear faster than the light, so even a lifetime with her. Please allow me to live." Having finished praying he looked down at the pond for a while and then suddenly turned around and left the forest. Old and sick the Elyos warriors also disappeared with Kata and haven't returned to the forest since.
