Orange is a poignant age gap romance manga that tells the story of Naho Takamiya, a high school girl who receives a letter from her future self. The letter warns her about the regrets she will have if she doesn't change certain events in her life, particularly involving Kakeru Naruse, a transfer student with a tragic past. As Naho tries to alter the future, she develops feelings for Kakeru, leading to a heartfelt exploration of age gap relationships, second chances, and the power of friendship.