In front of 17-year-old high school girl Kayo Hanazono (Momoko Tanabe), suddenly, 'I' (Kayo Noro) who became an Arasa from the future came! And a warning! 'I'm single for the rest of my life, and even if I reach 30, I'm a virgin! A childhood friend, Shinnosuke (Takumi Kizu), who is even more worried, will marry a classmate different from Kayo! Kayo, who was told the fact of the shock, started her actions with Arasa, saying, 'I have to turn around Shinnosuke and change the dangerous future!' However, a mysterious handsome Taki (Fuju Kamio) aiming for Kayo, and Shinnosuke's future marriage partner Kushida (Mei Tanaka) have appeared, and a square-related battle of love breaks out! Can Kayo change the future?