The leader of the tennis club, Kaori Kitamura, has been forced into a three-way sexual relationship by her younger and envious clubmate Ami. Kaori is forced to have sex every day, but she's still trying her best not to let it influence her everyday life. Still, after knowing such real pleasure, Kaori can't focus, and her body doesn't handle the morning-after pill well. The daily fuckfest makes her lose her position as the best tennis player at school. However, her childhood friend Seiya noticed the change in her. He realized that it started the day Kaori went to Ami's house. After that, Kaori said she was helping Ami with her studies, so they were holding studying sessions at her place every day, but she's been really weird since then. Seiya talks Ami into letting him take part in one of their gatherings, and so he goes to Ami's house on the weekend for an overnight study session, but...