Scum don't typically think about such things. Scum Marisa, here, sees a house that the family could live comfortably in, and is gonna kill the current yus living there. The little box is basically the training ground for yukkuri for Mr. Breeder. Of course, scum Marisa doesn't know this. Nor does it matter. Scum will kill any yukkuri to take something.
She got selfish. She probably could've gotten away with just stealing the food, but she had to go after the yukkuri.
Marisa~Marisa!!YunyaaaaaaaMarisa!She's lateRei-Re...Rei...mu...
he..help....W-who!?Yu...You small fries!
Be obedient and let the great Marisa kill you!