Mina Sugiura works days and nights trying to pay off the debt of her gambling-addicted husband. Recently, she's grown tired of her day job at a major precision machinery manufacturer due to the constant sarcastic remarks and petty criticism from her coworkers. Her only place of refuge at the office? The Reference Room, where she can vent to Tepps, an older worker who's past retirement age (as well as enjoy occasional games of Go with him). Rei Saegusa is hired to investigate into Mina and Tepps by someone who suspects them of having an affair. However, this individual has a secret, and all's not what it seems...