In the Binfield Kingdom Chronicle, it is said that there was once a small, peaceful country called the Kingdom of Winfield, whose king and royal family possessed great white wings. Hamura Shou is newly enrolled at Yuusei Academy. After hearing about a student named Misonou Kai from the heaster, Shou comes to believe that Kai is his younger twin brother, who he was separated from when he was younger. However, after a mysterious earthquake, Shou is suddenly carried into another world with two other students. It is in this new world that, after being attacked by a monster, Shou suddenly unleashes great, white wings.