The story takes place in the daily life of high school students in modern Japan. Guest and Rino are childhood friends who live next door to each other. Having spent almost every day together since they were small, they are close enough to walk in and out of each other's houses freely. Whether at school or after class, they can talk about anything without hesitation. However, they are of the opposite sex. No matter how close they were, they never spent the night together. One night, when Guest pulls back the covers to go to sleep, for some reason, their childhood friend Rino is hiding there.

They haven't had sleepovers since they were little, and their skinship was limited to hugging. Since middle school, they haven't really touched much at all.

They are in the same class at school and spend almost every break talking to each other. People around them wonder why they aren't dating despite being so close, and if they ever did, they would be the class's officially recognized couple.