The Devil Is a Part-Timer! light novel Volume 20

Do you want fries with your hellfire?
Acieth has been exhibiting strange symptoms for quite a while, and now her sister Alas Ramus’s condition is worsening, too! To aid in their care, the Devil King convinces Emi to let him stay at her apartment in Eifukucho. Between the slippers he’s been provided, the large refrigerator, and the fact there’s an honest-to-goodness bath in the place, Maou is floored by how different the Hero’s abode is compared with his spartan, one-room Devil’s Castle...as the group becomes the world’s strangest nuclear family. Meanwhile, preparations over on Ente Isla are entering their final phase. Will their ersatz rocket ship successfully take to the skies, at last enabling the invasion of the heavenly reams?