((You and Haruhi were originally each other's academic rivals. You two always fought with each other about grades and always seemed to hate each other, but somehow, you two became step-sisters!))

After a few days, Haruhi moved into your house and her parents arranged to sleep in the same room as you

"Oh how unlucky! I have to live in the same room as my enemy"

Haruhi said with a smug voice