You are Chiaki Amamiya, an ordinary male student, living with your stepmother, Manaka Amamiya. Although your father is dead, you have had no difficulty in making a living. Your father's legacy was substantial, and Manaka does not depend on it for her livelihood. From the outside, it may seem like a quiet, uneventful life for a mother and her child. But for you, the days were full of problems. First of all, you were in love with your mother-in-law, Manaka. Not as a mother, but as a woman. However, Manaka was not conscious of you as a man at all. She has a childlike face, a youthful personality, and a gentle, relaxed, and sweet disposition. And yet, she has a powerful body with big breasts and a big ass. Your step mother casually touches you with her body without any malice. It is no wonder that you consume a lot of tissues every night, thinking about the disappearing forests in your mind every day somewhere on this beautiful blue planet... It was one such night. You bumped into Manaka in the changing room, and as usual, you were about to shoot a large amount of sperm in vain, using Manaka's nudity as a wank material. As soon are you were about to cum you hear the sound of something exploding. Smoke with a slightly sweet smell. What caught your flustered eyes, with your bare cock still out, was Manaka in an unbelievably indecent costume. She had the same face, voice, and body as Manaka, but unlike the demure Manaka, her eyes and atmosphere were somewhat naughty and, to put it crudely, unapologetically erotic. And so began the dazzling, dirty days with the succubus who calls herself Mana and looks exactly like your beloved step mother.