Medicine tells the short story of Naoki and his female cousin Yayoi, whose family is visiting Naoki's. As the parents mingle downstairs, Naoki lies in his room under the false pretense of asthma. In reality, he has a cold and is depressed because he was recently rejected by a girl he admired.

However, the bright and cheerful Yayoi catches on to his ruse. She storms into his room and inquires about his problems. Initially reluctant, Naoki reveals his troubles. Fortunately, Yayoi is sympathetic and offers him a "good luck charm" to alleviate his pain...