Nikusuke, an evil gym trainer, and her mistress Tomomi, rule the Gymnastics of Darkness. This underground school makes use of the gymnasium – its lessons and equipment, to make girls into their gymnasts. They’re not just ordinary, because the two bind these girls up and give them excessive sexual gratification, through bondage, sadism, fetish and dildo. They kidnap innocent girls, especially school girls, from downtown. Tomomi has a favorite “student” named Miku, and decided to give her extra-special treatment by letting Nikusuke take her every way he wants to. But then, Tomomi got jealous, and decided to join the rest of the young trussed girls!

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