Well, let's see. It didn't really start until after the second murder, if the lights at the opera house were your own work, as you said. On both the second and third weeks -- and this one, though the pattern so far indicates that we're still too early to see a result -- someone elected to make a deal to have a hint revealed, assuming Shin still counts in that regard. If we believe that taking a hint means trading a part of your soul, and that souls are what she's after, along with usable power, it seems like there could be some connection to that. Or it could just be the souls of the dead, and there wasn't enough of a... stockpile, so to speak, until after the second week.

My own world's technology relies on spirit fossils, including our electricity, so this all doesn't seem that farfetched to me.

[ What else is there to add... ]

Each time so far, the places that have had power restored have been within one general area at a time, so it seems that certain parts of the power grid are gradually being brought back online, not that individual buildings are having it restored haphazardly.

That said, it doesn't really explain the particular timing. It's happened on Wednesday nights both times so far, I believe? And the fact that you're so curious about this is curious in itself. Does she know why it's happening?