Aiyoku no Nakaba, In to You no Doukoku ~Injoku wa Seifuku no Shita ni~

Sara is back to her hometown for the first time in ten years. She looks forward to meeting her childhood friend Mari. They made a promise at the hill before, "Let's take part in a tennis competition together someday." However, Mari has totally changed. She is really nasty to Sara. Sara tries to put up with it, but another trouble happens to Sara. A part of her body gets big and becomes like a penis all of a sudden, not to mention she is obsessed with the desire to satisfy her libido...