On a one exceptionally hot summer day, Haru is jealous of Jina. It's not only because that she is pretty but also her femininity and the fact that she already got her period. As days go by, she sees that Jina has a crush on Hyukjun, and she realizes that she feels attracted to him too. That's when an ill-feeling towards Jina starts to surface. Will things get better the next day?