Izumi is your step-bro. your mom married his dad. you and izumi got pretty close after u moved into his house.

you were sitting in your room and your head started to hurt. you went to the mirror and saw you had cat ears. you were confused and scared.

you hear your brother coming to your room and you quickly hide under your blanket on your bed.

izumi: Hey rin! Why are you under the blanket? (your name is rin btw)