When Arah was a small girl, her parents died in an accident. She grew up in her aunt's house. Arah, lonely without any friends, is abused by her aunt and cousin. In an attempt to get away from her aunt, she is hit by a car. Arah wakes up in another in a baby's body.

The Demon King, blinded in rage at the pain of losing his beloved Sain, tries to kill his baby. He hesitates to realize the baby looks like her. That's when Sain's spirit appears and asks the Demon King to take good care of their baby. The Demon King grows to love his daughter. He even learns how to take care of babies.In the meantime, Arah realizes she's been born again. She wonders who the handsome man who appears every time she needs somet...

The angels who have appeared adore Irene, but they know nothing about taking care of a baby. Irene is Sain's daughter, so he first watches after her with a sense of duty. As time passes, he gradually opens up to Irene and truly cares for her.

Kalavan takes Irene to the room with Sain's portrait. Irene realizes who her parents are. The God of the Heavens commands Raphael to be Irene's godmother. He takes care of her with Harchen. When Irene is alone, her grandfather appears to her. He can read people's thoughts and finds out she remembers her past. He introduces himself to Irene as her grandfather and says he will give her a gift.

With the flash of a light, Irene moves to another place. There, she briefly meets her demi-god mother. Irene is now three years old. Kalavan, Harchen, and Raphael shower her with their love by her side. Kalavan learns that there are forces that are targeting him in the Underworld.

Kalavan feels that his life on Middle Earth, where Irene is, and his work in the Underworld are becoming incompatible. He still has too many enemies to give up his position as Southern Demon King. He decides that he needs to keep his power to protect Irene.He leaves for the Underworld, leaving Irene in the care of Harchen and Raphael. Irene feels lonely at her father's sudden absence.

Irene feels lonely when Kalavan leaves her without saying a word. Raphael worries that Irene is mentally too mature for her age, so he plans a picnic for her. At first, Harchen is against it, but seeing how happy Irene is, they end up going on the picnic together.

Irene, Harchen, and Raphael are enjoying their picnic. A red dragon hatchling named Leiga is watching them from behind some bushes. When he is discovered, he starts bad-mouthing Harchen and Raphael, which puts Irene in tears. Leiga says he is 495 years old, and Irene lies about her age in hopes of becoming friends. He forms a crush on her and follows her back to the castle.

After the picnic, Leiga came to the castle to play with Irene every day. Harchen and Raphael were worried that the Demon King would be furious if he found out, so they spoke to Leiga's parents to keep him from coming over anymore. Irene felt sad.Irene falls asleep very sad. She has a nightmare about the time she and her parents were in a car accident in her past life.

Irene has a nightmare about a car accident that happened in her past life. A person approaches her through the flames. After realizing it is Kalavan, Arah changes back into her current self, Irene. She is in Kalavan's arms and awakens from her dream. She is sad to find that she's alone when Kalavan, who has returned from the Underworld, comes into her room to hug her. Kalavan has defeated his enemies who plotted against him in the Underworld,...

When his subordinates fail to get rid of Kalavan, Giatone decides to take matters into his own hands. Irene goes on a picnic with her father and meets a fairy princess, who she brings back to the castle. Later, Legia, who was unable to visit Irene for a while, appears at the castle gates with his father.

Rekan has come to see who his son Leiga is infatuated with. He ends up fighting with Kalavan, but everything is resolved in the end. Irene confesses she lied about her age to become friends with Leiga, permitting them to play together again.

Kalavan receives a name along with a sword from the Demon God. He becomes the Southern Demon Lord. Kalavan goes to Middle Earth with the other demon kinds to destroy the monsters there when he meets his fate, the love of his life.

Kalavan meets Sain and falls in love at first sight. He gains access to a dimensional travel permit with the help of the Demon God and travels to Middle Earth to see Sain.

Raphael doesn't like Kalavan spending time with Sain. Raphael and Kalavan are constantly bickering, and Sain is stuck between them. Kalavan arrives at Sain's masion. His traveling back and forth from the Underworld to Middle Earth caused him to worry about her safety while he was gone. It's night, and Sain comes to Kalavan's room.

Light and darkness. Sain is afraid to accept their opposite fates. She musters up the courage to propose to Kalavan because of his devotion to her.Sain and Kalavan marry by themselves, and Sain becomes pregnant. Kalavan is still going back and forth from the Underworld to Middle Earth. As Sain's belly grows, he is worried that he might not be able to be a good father. Sain reassures him that he will be the best father to their child. In the p...

It is Irene's 7th birthday. Raphael is away on business, and Kalavan and Harchen are also out. Leiga is stuck babysitting, so he can't come to see Irene. Irene is bored with no one around. She decides to go to the flower field but gets lost in the forest.

While Irene is lost in the forest, she comes across some knights fighting off monsters. The knights think she is an orphan and take her back to the town. On the way to town, a troll appears and grabs Irene. At that time, Kalavan, who had lost track of time buying Irene's present, senses that something is wrong and goes to track her whereabouts.

Kalavan senses Irene's location and saves her from the troll. When Luberruin sees Kalavan, he feels a mysterious power coming from him. Irene, unconscious, sees the hard lives she's lived in the past. She realizes that she has gone through several reincarnations of painful lives. Now, she is confused about her identity.She is transported into a mysterious place. She meets someone there.

Irene meets Erin in a mysterious and beautiful place. Irene learns that this place is inside her mind. She is advised to think of the precious people around her and think of herself as just herself and no other. She wakes up from her deep sleep. In the meantime, the Eastern Demon Lord Taladuke joins hands with Giatone to fulfill his ambition.

When Irene recovers, she learns how to handle mana from Harchen. Irene was only taught the basics but was able to use mana right away. Irene asks Lil, who came to play with her, about the girl Erin that she met in her dream.

The Demon God comes to see Irene. He takes the seed of misfortune within Irene for Erin. Then, he orders Kalavan to take Irene to the Underworld. Irene sees Erin in her dream again. Erin leaves her bird to Irene. There is an implication that she and Irene may be the same person.

As always, Irene plays with Leiga. Leiga's mother, Nebia, and aunt Teishan come to get him. As Irene watches them return home through a mana portal, she hopes that one day, she can use that kind of magic, too. Irene fell asleep at her desk while studying. In her dream, she saw the moment young Erin could control mana. Irene wakes up and succeeds in opening up the path of mana, just like she saw in the dream.

Irene is visiting Teshan's house. Teishan shares memories of Sain and also reveals her painful past to Irene. Teishan had lost her son and lived in rage, but Erin was able to save her from herself. Teishan gives Irene an artifact she meant to give to Erin in the past.