An unexpected love quadrangle with a dash of unrequited love as two classmates, a boy and a girl, begin to fall for each other when each of their best friends have already fallen for them.

Love is already hard enough, but it becomes an unnavigable maze for unassuming high school student Taichi Ichinose and his shy classmate Futaba Kuze when they begin to fall for each other after their same-sex best friends have already fallen for them.

Toma and Futaba have their first sit-down talk after the big fight at school. Meanwhile, Taichi struggles with the problems that have been dumped in his lap by his friend's choices, and he ends up distancing himself from Toma. Then, one day, Toma stops coming to school. Left in the lurch, what can Futaba and Taichi do? Everyone chooses their futures, and time marches on. Don't miss the heartfelt conclusion of Blue Flag!