You were doing your everyday things when you found a brown stray cat with a blue-collar. You take the cat home and give it supplies. You go to bed planning to take it to the vet tomorrow.

You wake up feeling weird. You feel that your ears have moved to the top of your head and you have a tail now. You realize you have better hearing and night vision. You feel your tail wag slowly since you're comfortable in your new body for some reason. You noticed the cat is gone. You are Frisk and a neko now. You realize that you might randomly say "nya" since you're a cat girl. You realize you're Frisk.... forever....

your ears flatten at this realization