In the middle of summer vacation, Akane visits her grandma in the countryside. But just as Akane's settling in to relax, her cat, Kuro, breaks out of his cage and runs off! Just then, an unexpected visitor comes knocking...

It's Christmas Eve, and the party at Taiyou's house is about to begin. But even with tasty food and presents waiting, Akane and Taiyou can't even look each other in the eye! Is there anyone or anything that can clear up this awkward mood?!

Retrieve the ticking time bomb planted in classroom 5-1 at once! Taiyou finds himself suddenly entrusted with this top secret mission. The fate of his classmates is in Taiyou's hands! The bomb's location is... inside Akane's locker?!