Won Mi-ho is the only heiress to the Daehan Group. She falls for her aunt’s plot and becomes the center of a controversy after beating up a person in the middle of the city. Mi-ho is sent to Jeju Island until things quiet down, but she comes across a lust demon in a wedding dress.

Not only was Mi-ho chased twice by lust demons, but the police are now also treating her like a drug user. She is trying to come up with a plan to escape Jeju Island and go back to Seoul. But before she could get on a plane, she ended up in a life-threatening car chase with a lust demon.

Johan moves into Mi-ho’s villa to live with Van and Mi-ho, disguised as Butler Jang’s nephew. Mi-ho is displeased with Van, who doesn’t seem to cooperate and can’t even drive a car. On top of that, Johan starts tagging along to school.

Mi-ho meets the last of Benjulle’s trees after a fierce battle in Benjulle’s forest. Mi-ho returns to her villa after saving Su-ryeon and starts planning on how to punish Gyeong-jun. Meanwhile, Johan provokes Van to find out his identity, summoning the hidden nature of the lust demon. Mi-ho comes to look for Van and Johan and sees Van transforming into a lust demon.

Van feels guilty for nearly killing Mi-ho and disappears into the darkness. To find Van, Mi-ho goes through rough mountain tracks to Taejangsa Temple, only to walk away after being hurt by his coldness. Meanwhile, the number of mysterious murder cases where the organs were extracted from the victims is increasing all over Jeju Island.

Johan brings Chan-hee to the villa. They spend time happily together, promising each other that they would not part again. However, Chan-hee has already turned into a lust demon, and he leaves Johan’s room to go after Mi-ho’s life. After finding out about the secret of reincarnation, Mi-ho visits and asks Geum Baek-ju to help her become Wonjeong.

Long ago, Jeju was thrown into confusion by an outbreak of lust demons. Wonjeong, fated to save the island by establishing the Barrier, secretly visits and forms a friendship with two boys, Van and Gungtan, who were raised solely to kill lust demons. Ten years later, Wonjeong returns to Taejangsa Temple after completing her training to establish the Barrier.

Johan overcomes his despair after Chan-hee's death. Mi-ho, who is in pain and blaming herself, vows not to lose anyone else who is precious. From then, she begins receiving intense training from Geum Baek-ju at Granny Haenyeo's Home to regain the power of Wonjeong. Johan and Van follow Mi-ho but observe from a distance so that they don't interrupt her energy.

Gungtan remembers once again that Wonjeong had sealed him in the past and escapes without being able to harm Mi-ho. Captivated by fear and anger, Gungtan begins to plunge the world into darkness. Mi-ho starts to blame herself, believing that the tragedy will only end when she dies.

Mi-ho finds out about Butler Chang's secret and tries to kill herself as she feels betrayed. The moment Van rushes to Mi-ho and holds her hand, she recovers all the memories from the past. Gungtan rages as he feels dejected after watching Mi-ho fail to regain power even after her memory has returned.

Van learns that Mi-ho will vanish if she regains the power, leaving only Wonjeong. After agonizing, Van tries to stop Mi-ho’s training to become Wonjeong. Mi-ho is just frustrated and upset at Van’s sudden behavior.

It's finally the day to establish the Barrier. Mi-ho, on her way to the altar, fights a great battle against lust demons alongside Butler Chang, who has returned, and Johan, who woke up from a coma. After defeating countless lust demons, Mi-ho leaves the rest to Van, Johan, and Butler Chang and goes up to the altar.