Naoko Noda, who works in a trading company, is called "anego" by her younger co-workers. What is "anego?" It means "older sister", but in this case it is given as a nickname to Naoko because she is like a big sister to the other workers, who depend on her to give them advice about everything. This drama, based on a popular novel, depicts realistically how Naoko lives her everyday life, including her love life, the problems she faces, and her uneasiness about the future.

Naoko, 32, works in the corporate strategy division. She is single, and has been working hard for 10 years, now she often finds herself in the role of training and guiding the younger female workers. Recently she realizes that most of the temporary and contracted workers' goals are to find an elite male employee within the company to marry.

One day, Naoko goes out to play golf with the general manager and other co-workers, and there she unexpectedly meets her former co-worker, Eriko Sawaki. Eriko seems to have a picture-perfect life; she is married to a company president, and already has one child. Naoko gets distracted by Eriko and the happy atmosphere around her, and ends up with a terrible golf score. After finishing the round, Eriko's husband comes to pick her up, and Naoko is surprised when she sees his face. Eriko's husband is the handsome man who saved her from the drunk man. Naoko's heart starts pounding, and she can't help but envy Eriko's happy life.