Tsukasa was not a simple man like everyone else, he could see the future from birth, but for the sake of this gift he had to sacrifice the past. He lived every day like a new one. Memories of the past disappeared with the advent of a new day, and so he lived for 17 years. He knew when the day of his death would come and what would happen in the future, but only about himself. One day, while going to school, he noticed Rui's boyfriend and remembered that in the future they would become best friends and Rui would make him happy. Tsukasa confidently ran up and grabbed Rui's hand "Rui, you are my future best friend!"