Masaya is a university student who works part-time as a home tutor. One day, he receives a parcel containing a notebook. He frowns upon reading a letter included in the package, which states, "If you write a girl's name in the notebook, you'll be able to control her as you like." Although he initially finds the claim ridiculous, he decides to test it. He writes the name of his student, Yumi. The notebook proves to be real, and he has sex with her. "This notebook is proved to be real. I can now have fun with it...." Based on a h-game created by Undermoon studio.