Suddenly living together with the older sister he used to love? Moreover, suspicions of being a slut have surfaced!? Naoto Kiyoshi is a young man who passed the university entrance exam. When he was looking for a place to live before moving to Tokyo, he ended up living with his relative Luna, his older sister whom he admired.The moon that she once admired has matured and become beautiful... and turned into a bitch! Naoto is surprised to hear her voice crying every night.Even though he is with other men, he is extremely close to me. He is at the mercy of the moon, who does not know what he is thinking, and even more so.Girls who are naughty and have strong habits are also gathering...!? Bitch? The beginning of a fun new life surrounded by older sisters.