Episode 16 starts with Sung-Yeol trying to find out what the light was on Seul-Bi’s wrist and Woo-Hyun ignores his questions and doesn’t tell him anything. Sung-Yeol finds a angel turned human book in Woo-Hyun’s bag and finds that the light will shine when in danger on their wrists and Sunbae lifts up the book and freaks out Sung-Yeol.
The next day at school Woo-Hyun and Sung-Yeol talk outside and Sung-Yeol tells him that he thinks he knows Seul-Bi’s secret and Woo-Hyun tells him to not say it. Jae-Suk talks his tall gang members phone away and says he is using his data now. Sunbae then turns up the volume on the speakers at school and Sung-Yeol’s and Woo-Hyun’s conversation is able to be heard through the whole school and it is revealed that Mrs. Ahn is Sung-Yeol’s stepmom and Woo-Hyun’ s real mother.
Jae-Suk then makes the tall guy bring Byeong-Wook to him and he tries to drag him and tells him to go because he didn’t have his phone to even warn him. Jae-Suk then comes out and says he should have Byeong-Wook’s phone instead then. The two of them then run away from Jae-Suk and he follows Byeong-Wook. At the restaurant Byeong-Wook comes in and asks the group if Tae-Ho (tall guy) had been there because his dad got into an accident and he is in surgery now. Joo-Ah waits outside for Tae-Ho and tells him to go to the hospital and Byeong-Wook soon follows after him to the hospital. Woo-Hyun is in the restaurant alone when everything starts moving and shaking and he yells at Sunbae that him and Seul-Bi will never be separated and then runs out finding Seul-Bi and taking her with him.
At home Sung-Yeol and his father haven’t come home yet so Woo-Hyun is going to look for him. Sung-Yeol is at the police station and is in trouble for hitting a man and acts like he wants to be in trouble.
Sung-Yeol’s dad covers Sung-Yeol with a blanket in the cell and puts his head on his shoulder and goes to sleep. Woo-Hyun finds them and then leaves. Seul-Bi meets Sunbae and she asks him to stop hurting people and he says he doesn’t know why he is doing it and doesn’t know how to go back to being an angel and he is doing it because of her. Woo-Hyun comes and he tries to use his powers on him and she covers him and he goes in front and says he is okay as long as she is and Sunbae doesn’t do anything.
At school Mrs. Ahn pulls up in the car and parents are surrounding the car yelling at her telling her she shouldn’t be teaching ethics. Woo-Hyun helps her inside. In ethics class most of the students leave and don’t take the class and she kicks out Sung-Yeol for listening to music. Ye-Na is ignored at school and then eats her snack in the bathroom crying and Seul-Bi pushes a drink in her stall.
Tae-Ho comes into class and says he is going to kill Jae-Suk because he didn’t get to see his dad before surgery and doesn’t know if he is going to wake up and he punches Jae-Suk and Woo-Hyun and Byeong-Wook stop him.
Jae-Suk finds Sung-Yeol at the gaming place and he tells him that he has become a tadpole and that he is scared of being left alone again. Mrs. Ahn and her husband are in their bedroom and he is packing for a stake put and he tells her she can get another job and asks if she doesn’t know where Woo-Hyun’s father is and that is not good to leave Sung-Yeol and Woo-Hyun together. She asks him if he only sees Sung-Yeol and doesn’t see Woo-Hyun hurting and that she is not going to send him anywhere and that she is going to raise him. He leaves and Woo-Hyun is in the kitchen and has overheard them talking.
At school Seul-Bi and the other group put together a petition to keep Mrs. Ahn at the school and Woo-Hyun pulls her aside and is not happy that she is doing this and says he wants her to resign. Woo-Hyun’s friends go and try to get as many signatures as they can but they are still lacking. Sung-Yeol tries to get others to sign against Mrs. Ahn staying and Woo-Hyun gives a speech that he can’t call anyone mom but at least at school he could see her and hear her talk and be around her and that moves the students to sign for her to stay.
The angel human has a board meeting and he decides that since the students are so passionate about keeping Mrs. Ahn and that even teachers with bad personal lives can still change students lives for the better. He tells them that they need to fight back against the parents and that they need to teach them through their actions. He rips up her resignation letter and Kwang-Shik the teacher that was on leave also comes back.
Sung-Yeol at home is reading about angels and Mrs. Ahn comes in and asks what she can do to make him forgive her and he just acts mean to her and pulls out her necklace. He goes to throw it out and Woo-Hyun and Seul-Bi walk in and Woo-Hyun tells her to just leave it and she tries to grab it away from him and he pushes her down and the necklace breaks. Woo-Hyun gets angry and grabs in and he tells him he won’t let him have Seul-Bi and Mrs. Ahn anymore and Sung-Yeol threatens him that if he says Seul-Bi’s secret they will forever be apart. Woo-Hyun winds up his arm and Sung-Yeol’s dad comes in and stops him and tells him to get out of his house and this ends episode 16.