On a certain day of a certain year, at night, a strange phenomenon occurred. One of Echizen Ryoma's Himalayan cats, Karubin, suddenly evolved and turned into a girl, a girl with ice as her flesh, willow as her eyebrows, cherry as her lips, jade as her character, and innocence as her content. Female, but she also had a pure black tail, which swayed from time to time, but only at night, and it could only last for half an hour. Ryoma didn't notice it until one day when he took Karubin to take a bath, she suddenly appeared. Ryoma was innocent. . . . .
Speechless was Ryoma's only thought, because she regarded him as her brother.
One day, she was suddenly taught bad things by Renzu Yushi. What should she do? She learned to bully him. She learned to "tease" him. What should he do? He didn't object to being secretly kissed by her. He felt a very strange feeling. He was very scared. He began to alienate her deliberately. She was very sad. She ran away from home.
After running away from home, he realized that he couldn't live without her.