With the start of September comes a new school semester, and Akane finds herself seated next to Taiyou. As the class decides on new class reps, Akane finds herself being volunteered for the job, much to the chagrin of an unexpected rival...

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?!