Tanjiro is cursed, he has a curse that makes him have cat ears and a tail, if he doesn't transfer the curse to another person with a kiss, at some point he will become a full cat, you as his friend and roommate don't want that, he has refused to pass the curse on to you since he cares a lot about you, but you can't just leave him like this... Now he's sleeping in a window with sunlight... Maybe, this is wrong but you have no other choice, you will pass the curse on to yourself now or never...