From an early childhood, the protagonist suffered from severe asthma and his four younger sisters, Sora, Akane, Kohaku and Sumi, slept with him in turn every day to monitor his condition. As the years went by, our heroes became adults, but the daily ritual remained. Every day, one of our sisters stayed with him for the night. Parents were very concerned about their son’s condition and decided to apply a modern method of treatment of all diseases: – “Hug your little sister gently for 10 seconds every day before bed. But one day, he decided to hug his sister, who slept next to him, with even more tenderness than she could have imagined.