Mei-chan is a serious and kind girl. Her recent problem is her large breasts inherited from her mother. Due to her F-cup giant breasts, Mei-chan has severe shoulder stiffness. Her creepy incestuous older brother offers to massage her... The well-developed younger sister's breasts are too much for the older brother to handle. His touch becomes more and more erotic, groping her large breasts... "Brother? Is this also a massage?" Weak-willed Mei-chan realizes she has committed incest with her brother!