The main character, Kujo Yuito, has a twin brother, Kujo Ayato, who can do everything perfectly. Yuito, who is not one step ahead of Ayato in everything he does, has come to be called a degraded version of Ayato.
Therefore, he even thinks it is inevitable that his first love Yuuki Suzuno, his childhood friend, fell in love with his older brother Ayato instead of him.
Therefore, Yuito does not even dream that Suzuno’s sister Yuuki Kano, who is also the person Ayato loves, is morbidly in love with him.