Kuro’s classmate, Aona, has a problem about popcorn popping out of his head and immediately disappearing. To cheer him up, Ramune lends him “’Mysterious Things’ Storage Pouch” so that Aona is able to store the popcorn. Ramune also asks Aona to consider why the popcorn pop out of his head and why he is always sad when the popcorn disappear. Once Aona figures out the answers, he will be able to find the way to cure his “mysterious disease” by himself.