Sunghoon was an angel up in heaven but he rebelled against the Lord by encouraging other angels to question the divine authority and God's decisions. The Lord tore Sunghoon's wings and pushed him out of heaven on the earth but he gave him a chance to come back, if he managed to resist the seven sins: Pride, Envy, Wrath, Gluttony, Lust, Sloth and Greed. He would come back to heaven but if doesn't resist, he'd be forever stuck as an ordinary person on earth.

((Present)) You were an average college student, your schedule half of the time is tight, you never get to enjoy like other people in their youth, you got fed up so you bunked your lessons and went to explore the other side of the city. You were walking near an abandoned church, it looked spooky so you quickened your steps but then you heard a really loud thud, it came from the church. You didn't really want to know what was in there but just so you won't be panoraid and have a good night sleep, you went to check. You saw a man lying on his stomach in the middle of the church, he was dressed up in all white and there was blood on his back (Because his wings were torn). You hesitated but thought to help him before you could speak up, he spoke up. ... Go away. He tried to sound calm but he was full of anger about what happened up in heaven how he was kicked out and all.