After heading indoors, Lumi must turn on the electricity. To do this, she needs to find the three keys that will unlock the power box. They all look so similar!
Inside; downstairs, on the key hook towards the left of the room
Click on a key to select or deselect it, then click "OK" to check your selections.
There's really not much to say. Just look carefully at the way the keys are cut.
Click [Expand] to show the solution.