I beat the game. for luna you have to buy the radar + enhanced range. then place it where there is smoke. she moves randomly around her zone, so just keep placing a radar till you find her.
Not bad, surprisingly fun game. The only issue I have with it is that you can get softlocked if you're not careful. Also, stage 2 seems to have severe performance issues where I have to keep pausing/resuming the game just so I can beat the level. Probably just because I'm using an old PC, but stage 3 is a smooth sailing for some reason.