After her husband's death, stepmother Chitose finds herself burdened with overwhelming debt. Forced to sell their home, she moves in with her stepson, Yuma, into a cramped studio apartment. In the confined space, their bodies constantly brush against each other, and the warmth they share—along with the sweet scent emanating from Chitose's soft, voluptuous body—begins to stir Yuma's emotions. Her big tits and thick, supple ass ignite his sexual desire, driving him to the edge of arousal. Unable to resist, his lust gradually takes over, and without conscious thought, he starts deliberately grinding his hard cock against her body. Their relationship begins to shift, heading toward a forbidden new beginning—stepping into the realm of incest.