Satoko, a librarian is not confident with herself because she has never been in a relationship although she is 30 years old now. She encounters a gentleman named Ryosuke and falls in love with him instantly. A man who proclaims he is "Stendhal", the author of the French literature "Love Theory" suddenly appears in front of Satoko who hopes to change herself every day. It is a good thing for Satoko who is surprised at seeing this "illusion" which, in her mind, appears because she is so worried about her love. What's more, to make Satoko and Ryosuke have a blossoming love, Stendhal guides Satoko with love secrets and gradually changes her! In this way, they two will become closer. However, Satoko has a "certain past secret" she does not want to be known by anyone...