Mysteries - Is there any value in the secrets that will be revealed when you find lost pieces?

A woman was sent to the general affairs department of a medium-sized construction company where Natsumi KAGAWA (Yukiko Echigo) worked. A year ago, a woman named Hoshika ISHIKAWA (Mami SAKURA) had two appearances of her best friend, Shika, who committed suicide. However, it seems that his colleagues who know the history of Japan appear to be completely different from each other. what happened a year ago? That summer day when I went out in a yukata with my colleagues Yuka, Yasusato and Michiyo. Natsumi and his men run away in disarray, with the help of three men. The men's aim was history. to hire men and jealousy... What was it for ... Shika committed suicide. A year later, a star incense with a mere historical figure that appeared... Yuka, a former colleague of mine, has mysteriously died. there's something unexpected happening inside the company... what's going on in this company? natsumi starts to suspect the history, but...