Was admiring my Grom when I noticed...

At first I thought the bike was knocked over by someone or someone had hit it. However, there is no damage anywhere. I then noticed that the screw that holds it in is missing. It must have come out while I was riding the last time. Does anyone happen to know what size screw this is or where I can get one? Do I need a Honda provided one or can I just go get any old screw from Home Depot or Lowe's?