At the loading screen that features a trail of paw prints and a picture of Issun, press X to make the paw prints larger. On other loading screens, repeatedly pressing X will display paw prints. You can also add Demon Fangs to your inventory by pressing X on the longer loading screens. Press X over screens that feature a trail of paw prints until Issun appears. Big paw prints and a Demon Fang will appear. Quickly press X as fast as possible until a Demon Fang appears to add it to your inventory.