Living a monotonous life as a regular sixth-grader in a dull town, Naota Nandaba's world takes a peculiar turn when his brother departs for America. Left with his brother's remnants, including his ex-girlfriend Mamimi, Naota's routine is disrupted by the arrival of the eccentric Haruko Haruhara. This pink-haired, Vespa-riding oddball inflicts a bizarre injury on Naota, setting off a chain of events that thrusts him into a cosmic conflict of epic proportions. As Naota grapples with this newfound chaos invading his once-quiet life, the fate of not just Earth but possibly the entire universe hangs in the balance.