Orange follows Naho, a high school student who receives a letter from her future self.
This letter details future regrets and tasks Naho with making different choices, particularly concerning a new transfer student named Kakeru.
Guided by the letter, Naho navigates her sophomore year, striving to change the future and prevent the regrets her older self carries.
The anime focuses on Naho's efforts to protect Kakeru and the impact her decisions have on her present and future.