I never said it was *good* art. But also, darned if I can figure out how to use this. Unfortunate!
Running the .exe should open a tab in your browser, from there you can load the game folder data, either then export everything to look through it in your directories, or click View Loaded Files and then Sprite Data Storage. Ctrl+f, "sprite_npc_(npcname)_big"; all lowercase, to find specific NPCs files, which will have an image tab with the NPC's dialog image.