In this drama, we see four kind of angels. Yes, four … you didn’t read it wrong. Let me introduce them one by one.
1. KD’s superior (cr. to @immorethant)

He can open or close the doors to Heaven As we can see, he is far superior to KD as he can change his form and his function without getting noticed by humans and angels. KD can not recognize him, until he shows his original face. JKW didn’t recognize him either. He is the one who gives orders to KD and advises him as well.
2. Kim Dan

Our angel Kim Dan seems to prefer animals over humans because they are much easier to understand. I do think that he does resent humans to a certain extent, and this could be explained with his past life. The only human he shows a certain empathy to is LYS. But I had already explained earlier that LYS’s behavior reminds me more of a hurt animal that shows its claws because of the pain. The more hurt the “beast” is, the more violent and brutal it gets. Yet, we were shown that Kim Dan has no idea about his past and his life as human. Yet his past is definitely connected to LYS, but he is unaware of it.
Right now, KD is on a mission (kim.dan@goodmission.com). As you can see, his email address reveals a lot, it is for the good of KD and LYS in reality. In 100 days, LYS must have found love. Striking is that the mission never said what kind of love KD should find for her. He immediately believes that he needs to find a human for her. The more time KD spends with LYS, the more she softens and relies on him. She starts trusting him… We know that LYS resents God a lot. She prayed in the past that God would make her wish come true but it never happened. She was even willing to offer her rip, but what she got in return was that she lost her sight. In this scene,

we hear from Ni Na that LYS used to say that talents were given from above and they should give it their all so they wouldn’t be an embarrassment to those who could not be there. This shows that LYS was very religious and connected her faith to the ballet. As conclusion, she no longer believes in God due to her tragedies in her life. So what if the real true mission is not to find true love but love and faith in God? There is no coincidence that KD brought her to a temple where she can make a wish because by wishing something, it means that you acknowledge the deity’s existence. She is on her way to find her faith back. That’s why LYS will be able to get back her title “angel”. Back then, she used to be like an angel: polite, nice, loving and selfless (remember her rescuing a small boy, KD).
KD is a good angel hence his wings are white and glowing. They illustrate his innocence and purity. He might overstep his boundaries as he often acts like a judge: he punished the driver by ruining his car and letting the dogs run away. His judgement is lacking because he only looks at the surface. However, his actions are quite selfless, they illustrate his deep sense for justice and his big empathy for weak creatures (dog, cats and LYS as a visually impaired person). LYS’s despair moves him.
To sum up, KD is associated to selflessness, empathy and huge sense of justice, yet his biggest flaw is his “false image” about humans. He is too superficial in his judgement. Therefore when he acts around LYS, he shows more empathy towards the staff than towards LYS. The latter is a human but behaves terribly, that’s why he trusts more the others: he doesn’t perceive the evil intention of the aunt. He judges people by their manners and appearance. He rather scolds LYS for her rude behavior. All this underlines his naivety. Furthermore in the episode 3, he often uses the words “humans” implying that he is different from them and they are terribly flawed. That’s why he is turned into a human for his mission. That way, he will learn to differentiate more… the real evil humans are not visible. He is definitely too naive and trusting. Don’t forget that he asked Ni Na if JKW was a good man. When the ballerina replied that she couldn’t tell if the artistic director was good or bad, he was just cool, KD thought that this was a good sign.
Notice that KD is really on his own all the time. His superior doesn’t help him hence KD has no home. He had to sleep on the bench, until he met LYS again. His superior just gives him some advice and that’s it. He has no financial background (huge house, people he can call and ask for help aso). Finally, I would like to point out that KD has no control over the appearance of the wings. My supposition was that they appeared because LYS was about to get injured. His wings protected LYS.
3. The artistic director: Ji Kang Woo


Only in the episode 4, we discover that he is also an angel. However, his wings look different. First, we only see the shadow of the wings. As you can see, the wings are not visible in the next picture and this indicates that JKW is a different angel. It definitely looks like JKW is a fallen angel, especially when the beholder pays attention to his words. I will give more further details later. Just like KD, he also has a mission: he has to make her heart beat again.

He is inspired by his past love Matilda that’s why he watched a video of her. Matilda loved ballet that’s why he believes that bringing back LYS to the stage is his mission. Once she dances again, she will be moved and her heart will beat again.
The mission sounds similar to KD’s mission but there is a huge difference. KD’s goal is following: By bringing love back to her life, LYS will be able to find peace and happiness. JKW’s mission can not end well because the more he pushes her back to Fantasia and to the stage, the more he endangers her life due to the greed of her relatives and directors. KD told JKW that he wanted LYD to find happiness to which JKW replied that he had no idea what this meant. As conclusion, this mission can be considered as evil, however on the surface it looks like it is a good proposition.
He is offering fame, wealth and power to LYS which actually corresponds to the devil’s temptation. Sure, he needs to protect LYS from harm, since she has not returned to Fantasia therefore on the surface, KD and JKW’s actions look similar: protecting LYS. Nevertheless power, money, greed, envy are the consequences of this mission. That’s why LYS refused his offer in the first place and gave him money… because indirectly that’s what he was indirectly proposing. Becoming a ballerina and taking the control of that company can not be differentiated.
When we pay attention to JKW’s words and actions, the beholder can notice that JKW sounds like the devil. He advises Ni Na to be selfish, to put a good fight against LYS, not to focus on others (episode 4). He definitely shows no empathy for the young mother on the stage. He is able to convince Ni Na to stop protecting others. Little by little, he is leading Ni Na to the dark side in my opinion. She admires him because, although he seems to prefer LYS, he lets her believe that she has the chance to become the star of the new show. Ni Na believes his words and doesn’t realize that he is misleading as his primary goal is to bring back LYS to the stage. His evilness is not perceptible at first sight, just like Ni Na’s father who seems so gentle and kind, while in reality he lets his wife and daughter RN do the dirty work.
JKW is definitely obsessed with LYS because she resembles his past love. There is a huge difference between KD and the artistic director. First, KD has no memories from his past life, only the viewers know that LYS saved his life, when he was a child. Her words before the car fell from the bridge triggered something in him. He didn’t know why he saved her but he had to. Her words arose emotions in him. JKW remembers his past:

The loss of the woman he loved. She was killed by saving his life. As we can see, both women did something similar: they rescued a person.
The question is now: who was he back then? A human? I doubt because if he was, he wouldn’t remember his past life. I have the impression that he was an angel too, but an angel of death, the one who took the soul of humans. This means, he had a superior status than the actual KD who only took care of the souls of animals. I guess, he might have fallen in love with Matilda who was supposed to die. By disobeying the order, her destiny was changed and she sacrificed herself for him. My theory is that because he couldn’t bear the loss of Matilda, the real Devil might have tempted him with an offer: she would come back to life, he could meet her again. But we know that deals with Satan/devils are full of tricks… like f. ex. LYS looks like Matilda but she is a different person.
Moreover, don’t you find it strange that each time, LYS’s life was exposed to danger, he always arrived too late? KD was the one who saved her in the car accident, he was the one who protected her, when the chandelier fell… Each time, the artistic director came too late. Yet, JKW is not aware of all this. He believes to be the right person for LYS because he has the means and the knowledge. He never corrected LYS, when she asked him if he was the one who rescued her? She recognized his hand but he never saved her life. Secondly, he always appeared next to a crime site (the car accident, the chandelier incident, the rocks lying on the road on their way back after visiting her parents’ urns. He gives the impression that he is protecting her… yet he is often too late.
By comparing KD and JKW, I observe that the latter is richer and has more power than KD. He is able to get any information he wants. He just needs to call someone. This is important because this represents the power of the devil. Money, connection, power are the sources of evilness because they are linked to temptation. For KD, it is different. He can only rely on his abilities (his good qualities: his honesty, his empathy, his strong sense of justice aso).
I know that a lot of people dislike the scene between Ni Na and JKW but the more scenes we get, the more it becomes obvious that JKW is leading Ni Na to the path of evilness and self-destruction. In the scene above, where Ni Na and JKW are together, he reminds her that she needs to be even more selfish: “You’re still a long way from being selfish”. So at some point, she will hurt LYS herself. She is losing her purity little by little. Don’t forget that Ni Na has already be introduced in an environment of violence and pain. We saw her killing a cat (which was an accident). Nevertheless, this is no coincidence. Then we discover that she is suffering from an eating disorder which outlines her willingness to hurt someone. Her hands are not clean and she will do much worse in my opinion.
I am quite sure that JKW was jealous of KD, when he saw the couple kissing that’s why he reacted by showing his black wings. The more time KD spends with LYS, the more the latter will fall for our protagonist… at some point, JKW will be the one who reveals KD’s true nature to LYS in order to separate our couple.
So now, this is the time to reveal the identity of the 4th angel.

Mr. Jo said that she was like an angel. She used to shine so brightly. Sure, this is connected to the ballet. But deep down, I think that Mr. Jo wanted to see her huge smile oozing happiness and gentleness. Back then, she was a really nice person. By spending more and more time with KD, she will gradually change as she trusts him. He will bring her true personality to light, while Ni Na will become her shadow embodying evilness for real. She was like an angel in the past because she once rescued the human Kim Dan.