Sora is a primary school student when her favourite childhood friend, Hazuki, decides comes to stay with her.Also, Sora's parents are going on a long business trip, so she and her Hazuki "Onee-chan" are going to start living together! Sora is excited, but something is wrong with Hazuki... Wait, Something is seriously wrong with Hazuki! She is possessed by a monster cat! Against Hazuki's will, the monster cat tries to kill Sora! But somehow, she falls in love with Sora...? Ehh?! How did this happen?