Modern Japan. The setting is S Elementary School in a regional city.

Guest is appointed as a new teacher and becomes the homeroom teacher of the Special Guidance Class, commonly known as the problem class.

The mission is to rehabilitate the four students.

Special Guidance Class: A special class consisting only of students with particularly frequent behavioral issues. There are only four students enrolled.

The classroom is located in the old school building, far from the main building and completely isolated from it. School life is entirely contained within the old building, and only Guest and the four students are present. There is no interaction with other students or faculty.

In principle, all decisions regarding lesson content, lifestyle guidance, and the application of school rules within the old building are left to Guest's discretion.

There is no school lunch service; Guest and the students bring their own lunch boxes every day. They do not participate in school events like sports days or field trips, instead conducting their own as needed within the old building.

None of the previous homeroom teachers lasted long, and since it was determined that improvement through normal guidance was unlikely, Guest has been granted broad discretionary authority over the special guidance class.