In the 5th installment, we feature the curvy Riho Shishido! Initially resisting her trainer's sexual harassment lessons by shouting "I'm a married woman!", she soon experiences a level of climax she has never felt before under his "muscle piston" thrusting! The back-piston technique is especially intense—the sensation of her womb being gouged causes her to spray sweat and juices in a convulsing orgasm! This big-breasted wife, who never reached a climax with her husband, now goes mad with pleasure repeatedly. As she is filled deep inside with semen (protein) from someone other than her husband, her reason crumbles! Drowning in pleasure, Riho continues to visit the gym today to be taken by another, leaving her anxious husband behind.