Before reading this story, u should see the anime Charlotte first. Its actually the after story of what happens after Otsuoka Yuu loses his memories after completing the mission of saving the world. He even forgets the confession and the promise he made with his friend Tomori Nao. But Nao still loves him.
Right after Yuu finished his adventure in stealing all the power of the ability users. His brother Shunsuku came to his rescue. With all the abilities in the world but not a single memory about his life. What will he do from now on. About his life, about his friends, about his family, and about his love. P.S.: Thanks...