the game shop Sparkle goes to, Maze of Ith, is named after one of my favorite and most annoying Magic: The Gathering cards. i hope Wizards of the Coast doesn't mind.
the idea here is that it's not raining but Sparkle wears the poncho because in the area where the game shop is there are lots of leaky water pipes and the water is dirty and rusty. plus the poncho and galoshes are good as a regular outfit.