Tetrominon 
Undesirable
Here and in >>1326267, Luna is saying “Nenaiko dare ja?”, which translates roughly to “Who’s not sleeping?” However, there’s a bit more to it than that. The phrasing is a direct reference to Nenaiko Dare Da?, a classic Japanese children’s book about a ghost who goes out late at night looking for children who haven’t gone to bed as they should. This short animated adaptation doesn’t have subtitles, but the pictures should be enough to convey the gist of the piece.