1The sky is most beautiful in summer » There are 3 kids in the Sawada, a girl and a twin of two boys. How will Natsume keep the promise that she made to her little brothers Tsunayoshi and Tsunashige the day the twin were born when the two boys turned into enemies of each other? AU. No pairing. No incest. Un beta-ed. Rate T for violence scene related to a certain hitman and some certain characters' language.