Episode 18 starts with Seul-Bi in bed with a bandage over her wrist with the mark and Sung-Yeol is watching over her. Mrs. Ahn finds Woo-Hyun in pain. There is a flashback when Seul-Bi was an angel and Woo-Hyun runs through her. Mrs. Ahn has a flashback when Woo-Hyun was a boy and at a pool with her and she answers a phone call and gets notified she is a teacher now and Woo-Hyun starts drowning in the water and Seul-Bi as an angel knocks the phone out of her hand so she will see Woo-Hyun.
She runs into the water and the lifeguard helps pull him out and get the water out of him. She feels bad because every time he is with her he gets hurt. Seul-Bi wakes up and refuses to stay home and goes to school and Woo-Hyun also refuses to stay home when he wakes up. In his room stuff starts falling down on them. Woo-Hyun and Seul-BI meet at school and he tells her not to wait for him because he won’t be there. Woo-Hyun goes to talk to Sung-Yeol about what was wrong with Seul-Bi and he doesn’t tell him. In gym class they dump the balls and tell Seul-Bi to clean it up with her superpowers but she denies it and starts cleaning it up and all her friends join in and help. She starts getting dizzy and then faints and Sung-Yeol carries her to the infirmary.
Woo-Hyun’s heart starts hurting. During class it hurts again and Ki-Soo helps him also to the infirmary. When Woo-Hyun falls asleep Seul-Bi goes to him and almost holds his hand but he moves and she runs away.
Woo-Hyun meets Sung-Goo the angel turned human and he decides to talk to Woo-Hyun. Sung-Goo tells him that Seul-Bi has hurt the mark on her wrist and that they are sharing the pain that when you are in love you ache for another. He tells him that he will have to wait for the mark to heal and if it doesn’t then she will disappear.
Mrs. Ahn meets Seul-Bi outside the apartment and gives her a packed bag for her husband because of all his stakeouts. Seul-Bi gives back her necklace. Her husband meets her in the parking lot and he tells her he only sees Sung-Yeol and has been a terrible father and feels bad because when he was beginning to trust her this happened and it breaks his heart this had to happen. He wants her to leave Woo-Hyun and she disagrees and he wants to know if their relationship is over and she tells him it depends on him.
At school they are going on a field trip and Seul-Bi is tired and keeps falling asleep everywhere and Joo-Ah has to wake her up in the washroom. She tells him she will be in the garden because she is sleepy. Woo-Hyun talks to Joo-Ah and she convinces him that they need to tell their school the truth about Seul-Bi because she keeps falling asleep everywhere and wants the school to help them protect Seul-Bi. They pass out the paper explaining her situation and everyone finds out she is an angel.
Jae-Suk finds Seul-Bi asleep in the garden and he wants to see her wrist and before he can look Sung-Yeol stops him and tells him to get away. Sunbae comes and makes Seul-Bi disappear and Sung-Yeol gets mad and tells Jae-Suk to find her.
Everyone is out looking for her and a group of students find her and they want to find out if it is real and Young-Eun tells them not to. Woo-Hyun all of a sudden appears on camera and gives a heartfelt message about Seul-Bi and how he loves her and how he can’t live without her and it is broadcast all over the building.
Sunbae is there and Sung-Goo stops him from using his powers.
Woo-Hyun is crying and saying he misses Seul-Bi and asks her not to leave him behind and she comes from behind and hugs him and tells him she is always beside him and they hug and cry together.
All the students are touched by them and Ye-Na is upset and says she lost to Seul-Bi. Sung-Goo talks to Sunbae and he explains that there love is different they feel each other pain and that he is just feeling his own pain. Sung-Goo explains that he will not be able to use his power on them anymore and that if he gains Seul-Bi he will lose everything. Sunbae disagrees and is told that he has lost to love completely. Seul-Bi and Woo-Hyun go and find their friends and they are all wearing yellow bands around their wrist in a way to support Seul-Bi in hiding her wrist. They put them on and everyone gives her a high five and she starts crying.
Seul-Bi finds Ye-Na and she is crying and she tells her to be good to Woo-Hyun, Ki-Soo finds them and tell them that Young-Eun’s sister is in the hospital and they need to go to a big hospital to do more tests but cannot afford it. Jae-Suk tries to pick on another kid and Tae-Ho and Byeong-Wook stop him and they remind him to keep Seul-Bi secret or they will stomp him again. Sung-Yeol decides to let Seul-Bi go and kicks her out and locks her out. She says she doesn’t want to leave him and he starts crying behind the door and he tells her to leave when he is still able to let her and she apologizes for not being able to return his feelings.
Mrs. Ahn sends Woo-Hyun down to Sung-Yeol’s to bring some food and as an excuse to see Seul-Bi. Seul-Bi waits outside for Sung-Yeol’s dad to come home and Jae-Suk finds her and asks her about the secret and why they didn’t ask him. He tells her that he mad because Sung-Yeol turned his back on him and that it is her fault and he tells her he is going to reveal everything. Woo-Hyun while walking his heart starts hurting and Seul-Bi bangs on the door for Sung-Yeol who is in bed and he is feeling pain. Seul-Bi starts to pass out and her arm starts shining brightly and Woo-Hyun sees the light and Sung-Yeol passes out trying to get out of his room and this ends episode 18.