Hakata Soy, having recently fallen in love, discovers that a sinister culprit is stalking the halls of Astronaut Academy, impersonating the crush-objects of students and making off with their extra hearts.

"It's summer vacation for the students of Astronaut Academy, and Maribelle Mellonbelly is throwing the best party ever on Beach Planet? Yes! But tensions heat up fast when Hakata Soy's arch rival, Rick Raven, arrives. And soon the whole planet is heating up--with a giant volcano threatening to blow its top! Unless they can work together save the planet, the students of Astronaut Academy will be toast. But can they put aside their differences in time...