The main character, Munetaka Takesaka, fails in his first experience with a lover who has been dating for the first time from past trauma. It was his sister Ritsuka and his cousin Mashiro who
offered him a literally naughty lesson and help overcome trauma when he was depressed . However, because another older sister who made trauma to Munetaka, Wako, also participated in the war, it was no longer just a lesson …? The battle for the younger brothers of the older sisters is about to begin !!
