This game is half price on Steam, and there's a few things I figured out that might not have been mentioned yet:
Store atmosphere changes who shows up in your store:
Dark: Griff, Charme, Caillou, and that combo breaking ***** show up more often. The little girl NPC, Louie, Elan, and Tielle will show up less. If you go full dark, these characters will not show up at all (or very rarely).
Light: Louie, Tielle, and the little girl NPC show up more. The combo breaking loli shows up less. Griff and Charme show up less.
Plain: Louie, Elan, Tielle show up more, Alouette and purple loli shows up less.
Messing around with the store is useful if you want certain characters to show up for equipment more often. Tielle counts as a little girl, so putting lots of sweets in the window and making the place light gets her coming in a lot.