月に1回のPMS。生理前の絶不調な時でも白川さん（井桁弘恵）は強く、可愛く生きている。そんないつでもポジティブな白川さんを同僚の谷口さくら（藤野涼子）は露骨に避けていた。入社当初は仲の良かった二人。「女社会に順応できない似た者同士」だと白川さんに好意を持っていた谷口さんだが…。谷口さんが白川さんを避ける理由とは…？
さらに、谷口さんの悪意が加速してしまい、ある事件が起きる。挨拶さえも無視されてしまう白川さんが出した意外な答えとは？
PMS 1 time per month. Even when she is in a state of desperation before her period, Mr./Ms. Shirakawa (Hiroe Igiri) is strong and cute. Mr./Ms. Shirakawa, who is always positive, is blatantly avoided by her colleague Sakura Taniguchi (Ryoko Fujino). When they first joined the company, the two were good friends. Mr./Ms.. Taniguchi had a liking for Mr./Ms. Shirakawa as "similar people who can't adapt to women's society." Why does Mr./Ms. Taniguchi avoid Mr./Ms. Shirakawa...? Furthermore, Mr./Ms.'s malicious intentions accelerate, and an incident occurs. What is the surprising answer given by Mr./Ms. Shirakawa, who even greets are ignored?
