Where to find the mysterious dog's toy in Control Resonant

A mysterious dog can be found sitting on a rooftop in Control Resonant. When you interact with her, you decide that you need to find her a toy, which every good dog deserves. Luckily, one can be found nearby. However, it turns out that the mysterious dog will appear in multiple zones, so you'll need to find a bunch of toys in order to complete the "Every Dog Has Her Day" side story quest.