Shinya, who attends a university in Tokyo, returns to his hometown for the first time in a long time. While talking with his mother, he hears that his cousin Shotaro is visiting with his wife Sarina. He is surprised to learn that his cousin, who has always been boring, is married, but is even more surprised when he sees his wife. His eyes are glued to her huge breasts, which are hard to believe! What's more, his eyes are drawn to the deep cleavage that catches his eye. One day, he hears a voice coming from Sarina's room, so he peeks in and finds her exhausted after masturbating. Knowing that she is not satisfied with their nighttime activities, Shinya approaches Sarina and makes a move on his cousin's wife.