Haruki and Motoki, both high school seniors, are working on a spring break assignment for their “Character Documentary” paper, trying to uncover the sexual proclivities of Chisato, the student council vice president. Around that time, they spot a woman at a bus stop aggressively selling a probiotic drink called "Yökul". Captivated by how she holds the attention of passing salarymen, the two boys become intrigued by her…