It was my impression that the power went out with the lightning strike that happens when Yugami-Kun was leaving.
At the end of the previous chapter, Chihiro is sitting in her apartment watching the rain unperturbed, then opened the door for Yugami.
So she wasn't sitting around the in the dark.
I love that the cooking was well underway before Chihiro had her whiskey-tango-foxtrot.
So... has Yugami unconsciously been waiting for an invitation to touch her this whole time or...?