Makoto Niwa keeps a meticulous record of the positive and negative experiences of his youth, almost as if grading his own life. When his parents travel abroad, he seizes the opportunity to move to a new town and live with his aunt, eagerly anticipating a fresh start. Little did he know that his ordinary teenage life would be disrupted by the sudden appearance of an enigmatic, long-lost cousin. Upon arriving at his aunt's house, Makoto encounters Erio Touwa, his previously unknown cousin who is his age but vastly dissimilar. Instead of attending school, Erio spends her days wrapped in a futon, claiming to be an extraterrestrial being. With her bizarre speech pattern and personality, Makoto's hopes for a typical teenage life dissipate. As Makoto meets other peculiar girls in his new hometown, he may find his youth points in the red. Nonetheless, he may be pleasantly surprised by the excitement of an unordinary adolescence.