A new student's sick day is interrupted by a mysterious call from the school's president. Upon her return, his strange looks shock her, kicking off an unusual high school journey filled with surprises and unexpected twists.

Yuiko Yoshioka begins the first grade in high school. She gets sick with the cold and stays in bed. At that time, she gets a phone call from class president Matsubara. Yuiko becomes fluttered by his kind voice on the phone. The next day, she goes to school and meets Matsubara. He is a mysterious boy, wearing a paper bag over his head. Her high school days begin with pounding heart.