Mini Ninjas on Wii does not have a traditional inventory screen. Progression is handled through automatic collection and the main menu.
Unlocked via scrolls. Assigned to Wii Remote gestures (e.g., draw circle for Fire, slash for Lightning). No inventory management needed—just gesture to cast.
Summary: If you're looking for a "Backpack" or "Items" menu, it doesn't exist. Check the Main Menu to see unlocked heroes and magic.