From what I remember from the past chapter, I think all of them kinda have part in it. The girl decided to be nosy and give away the number despite being told to mimd her business. The black haired death girl didn't know when to give up pursuing the ml. The demon being a demon started this whole thing by giving the wrong number while seemingly knowing this would happened. He also led the death girl on a date and ditch her which got her harassed and the everyrhimg just went downhill for her from there. While the MC is the most innocent out of all except he's realizing that the demon plotted this whole tragedy and he's probably not gonna do anything about it making him a bystander since as he said, the demon is the only he have left and he's basically helpless against his manipulation and tricks.
agreed, the mc is manipulated by the demon and feels guilty because the demon "did so much to him". its normal for him to feel indebted to the demon. Kinda felt bad for Yaoyao. Im still wondering what type of demon Bai is, since he isnt a contract-type demon. (Im still not sure about that) The demon was jealous, he thought that the MC is going to be taken away from him. Im still confuzzled of the mc has feelings for the demon. Its kinda weird lol ┗( T﹏T )┛
Its your fault btch, if u didn't gave the number then it wouldn't have happen lol...