Kyoshitsu ga, Hitori ni Naru Made

A series of student suicides strikes Kitakaede High School. One student hanged themselves in the school restroom. Two jumped to their deaths from the school roof.

Each of them left behind a suicide note containing the exact same phrase: "I was too loud in the classroom. I need to be tuned."

To Tomohiro Kakiuchi, these three deaths were undeniably suicides—or at least, they were supposed to be. That is, until he heard the words of Mitsuki Shirase:

"None of them committed suicide. All three of them... were killed by Him."

The "Worst" crime committed in the "Best" class. The curtain rises on the loneliest mystery investigation of all!