Mitsuko Kuroda is 31 years old and single. She enjoys her life as a single woman. A big reason why she enjoys her single life is that she has counsellor \"A\" in her mind, which is her other self. Whenever she does not know what to do, \"A\" gives her the right answers. She believes her happy and peaceful single life with \"A\" will continue, but she falls in love with Tada-kun. He is a salesperson and younger than her.