[X] Have everyone else talk to the shop owners and fish for information and generally be a distraction even if they aren't giving up anything. You'll sneak in the back and other areas to check things there.
[X] Write-in: A mixture of Midori's and Pallavi's suggestions would probably give us the most time to work with, since we can fish for info AND act as a distraction to keep attention away from whichever of us start snooping around. The info-fishing team probably isn't going to get much, though, compared to the snooping-team.
[X] Support Pallavi's Suggestion. (Acting like a normal group of girls and asking about the shop's oddities might be the best way to avoid any unnecessary conflict, while getting a better idea of whether or not this whole venture is a red herring or not. If there is something up, you can ask more questions to try and trip them up.)