One day, Yusaku receives a big package. When he approaches it, a siren rings and it opens. There is a girl lying inside.... She looks like just a girl, but she has big ears and a long tail. Yes, she is a hybrid organic creature called "i-do Type F". As a matter of fact, he applied for a monitoring campaign for the i-do Type F a few weeks ago. She wakes up and tells him to name her. He decides to call her Felis. Like this, his life with Felis starts now....