Youichi is a very serious, stoic young man with a girlfriend and a regular sex life. However, he has never experienced sexual self-gratification.

Recently, he's become aware of a book called "Masturbation" at the library he works at—an educated discourse into the history of the sin of Onan and related practices. Finding himself increasingly intrigued by the concepts within, he begins to conduct a series of experiments... Join him as he embarks into a whole new world!

(Source: MU)