A Thief in Our Midst
The quest is unlocked after completing The Great Plateau scenario.
"Some dastardly crook is pilfering little by little from the Yiga Clan's precious banana hoard! Get yourself ready for a stealth mission... It's time to catch this mysterious thief in the act!"
"The "crook" turned out to be a small boy who loved bananas. Unable to find them at shops, he had no other choice... The Yiga, moved, decided to loosen their grip on the world's banana supply."