33-year-old Akiyama Satomi is a history teacher at the prestigious all-girls high school she once attended. She has earned the nickname "ohitorisama" (meaning "one person") for her perfectionism and capability to handle any work by herself. At the same time, the name also refers to her lack of romance. One day, a young man named Shinichi arrives at the school as a temporary instructor. He's ten years younger than Satomi, has only worked part-time jobs, and has neither money nor status. Although the other female teachers and students find him cute, he is completely not Satomi's type... or is he? Will love blossom between this unlikely pair?

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...

Jina is the top employee at a credit card company call center. She avoids building close relationships, choosing instead to live and work alone – until she is suddenly tasked with training a new recruit.