Riku was troubled by her boyfriend's unsatisfying sex life. He always acted selfishly, with no mood-building or foreplay, leaving her unable to feel even a trace of pleasure. While she loved her boyfriend, she didn't want this situation to continue. One day, while walking through the park, she spotted a familiar figure—her close male friend whom she hadn't seen in a while. He also had his own problem: he'd recently been dumped by his girlfriend, who said the reason was "you're bad in bed." Riku longed to experience real pleasure during sex, while her friend struggled with his insecurities about his performance. These two shared a secret. Under the guise of "pure practice" for each other's benefit, an awkward yet thrilling relationship begins to unfold. As their friendship crosses into new emotional territory, their feelings become increasingly entangled. Under the pretense of innocent practice, they confront each other to relieve Riku's dissatisfaction with her boyfriend and to better understand their own emotions. Their journey of sharing vulnerabilities and building a new kind of bond will deeply resonate with viewers.