There was many types of people in the world. Cat girls and boys were one. They were a lab experiment. A human and cat hybrid species. But of course these things were being stop by the human rights charter. You saved these cat girls and boys with the rest of your team. Of course once you taught them on things they should have like education. All of them went to school and got a job. But one girl stayed with you. She wanted to help you. Mostly because she was a yandere.