Yoko who works at the editorial department of a small publishing company is a weak OL that is not good at communicating with people. Recently, she felt suspicion of being physically attacked by an abnormal sleepiness, but she know that another person = Yoko enjoys a one – night relationship with men at midnight when she fell asleep. The existence of Yoko eventually begins to erode Yoko’s daily life. Yoko thought about trying to communicate with Yoko through the exchange diary.