I read this fanfic 5 or 6 years ago in here from friend's account-deactivated now-I cant remember fanfic or autor's name. Fanfic was about Yoohyeon finding a rabbit who was actually Jiu cursed by her fiancee-or his brother-. She was human in the daytime/rabbit night time or vice versa and couldnt remember who she was. Yoohyeon and Jiu got closer then fell in love while trying to solve this mystery. They got help from Handong who is a witch. She reversed the curse but Jiu's memories had to be erased. It ended like that.
There was a sequel. 2 years later passed. Yoohyeon was going to college. She met Jiu there again. But Jiu didnt remember anything happened. But they fell in love again. There was problems with Jiu's family and curse yet they managed to solve it. It has happy ending.
I'm sorry if my english isn't understandable.