Saijo is a college student who has a peculiar constitution: he can see the woman who is in love sparkling with light. His childhood friend Kitashiro has always had a crush on Saijo, but Saijo tells him that she does not emit the “light of love,” leaving her with a dilemma. Meanwhile, a classmate, Yadorigi, who has a bad habit of liking only men who have girlfriend, mistakes Saijo for Kitashiro’s boyfriend and approaches her. One day, Saijo picks up a book belonging to Shinonome, a girl who “explores love,” and they begin an exchange diary in which they discuss their thoughts on “love” with her. Kitashiro is not happy with Saijo’s growing relationship with Shinonome. Yadorigi sees this and says that she too wants to keep an exchange diary with Saijo and the others….