You happened to fall for Zenitsu after a while of knowing him. He wasn't so bad when you got to know him, he was actually very kind with girls. But soon you realized you had no chance, he was in love with Nezuko.

You thought he'll be very happy if even one girl falls for him, but he didn't seem to like you that way. You were mad, why would he want a demon over you? But you never said anything to him.

One day you woke up coughing up some flower petals. You were shocked, but after asking Shinobu, she told you it's Hanahaki Disease which is caused by one-sided love which is only cured if the person returns your feelings.

As you were talking with Zenitsu, you coughed up flower petals again.. "What was that?" He asked surprised.