High school Fukurasuzume is one of the prefecture's most advanced schools. Ruled by principles of rigorism, it puts the students' discipline first. If a perfect high school exists, it must be it. As now almost everyone goes to uni, it is difficult for schools to stand out. Yet, it being so classy, everyone wanted to enter Fukurasuzume and not some other high school. It didn't become such a place out of the blue, though. In it, a secret organization handles all the misconducts of both internal and external parties. And it has a name - chemistry club. They deal with everything, starting from shoplifting and deplorable acts of theft to deaths, homicides, and disappearances before the police so much as catches wind of the fact anything happened. Yeah, that chemistry club is that influential. Don't ask me. I have no idea why that's the case; I'm just your regular investigator and all.

At the tender age of 18, he is an undercover investigator and the head of the Second Investigative Security Division of the chemistry club. As is appropriate for his age, he goes to school as a regular student and is tasked with preventing different trivial and not so trivial incidents.

However, one fall, our hero embarks on yet another investigation. That's when the story begins in earnest.

Our protagonist advances the story. It leads him to the truth behind the crime. However, he feels as if something isn't quite right. Why? Honestly, he has no idea. But he has thoughts in his head he himself doesn't quite understand. That's when our protagonist notices what this case is really about and the poison contained in it.