Lite is painfully shy and keeps his distance from classmates, especially women. Everything changes when he discovers a mysterious notebook called the Sex Note, which supposedly grants mutually desired encounters with anyone whose name is written inside. Initially skeptical, he soon meets Ricuk, the god of desire, who urges him to test its powers. Lite writes down the name of his teacher, Michelle, and is astonished when she unexpectedly shows up at his home, setting off a bizarre chain of events.