Acieth has been exhibiting strange symptoms for quite a while, and now her sister Alas Ramuss 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 hes been provided, the large refrigerator, and the fact theres an honest-to-goodness bath in the place, Maou is floored by how different the Heros abode is compared with his spartan, one-room Devils Castle…as the group becomes the worlds 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?