Ao no Flag

High school senior year, spring—one of life's important forks in the road. Taichi Ichinose finds himself in the same class as Futaba Kuze, who he feels strangely averse to, and his popular childhood friend, Touma Mita. One day, Futaba confides in him her love for Touma, and asks him for help. How will Taichi respond? This new “pure” love story begins as the three are colored in the emotions of youth.

(Source: MANGA Plus)