Forty-year-old mother with a big ass comes from her home in Morioka, Iwate to her son's apartment in Tokyo. During their long-awaited reunion, the son is captivated by his mother's unintentionally exposed underwear. With her voluptuous breasts and lush backside so close, his uncontrollable desire begins to stir. Unable to resist, the son seeks physical intimacy with his mother. This rare moment of mother-and-son closeness awakens primal instincts, leading them into a lewd and incestuous relationship.