When he finally emerged, damp-haired and wearing an oversized t-shirt, he looked at my makeshift bed on the floor and sighed. "You're really not going to make this easy, are you?" "Get some sleep," I muttered, pulling the covers up. "Goodnight," he whispered.
The keyword’s structure is dialectal (“de na” is common in Kyushu and parts of western Japan). Compare: shinseki no ko to o tomari dakara de na od hot