Bullied since birth, repulsive in every regard, and hopelessly in debt due to a cosplay obsession, Mitsuru Fukushima decides to end his dismal life to escape his sorrows. However, upon arrival at his chosen suicide spot he finds the body of Mitsuko Fukushima, who looks identical to his cross-dressing persona. Enchanted by the luxuries she left behind, Mitsuru impulsively abandons his suicide plans to take on Mitsuko's identity. However, his plans for a glamorous, carefree life are trampled when he finds himself taking over Mitsuko's job: a new teacher at Teihen High School, one of the most dangerous schools in the country.

Thrust back into the high school setting that tormented his youth, Mitsuru must now head class Tiger—home of Teihen High's most troubled and dangerous students. Although Mitsuru would like nothing more than to escape, his own bumbling attempts to do so—as well as a mysterious ghostly presence—prevent him from doing just that. As a result, he ends up inadvertently helping his troubled students with their own problems, glorifying Mitsuko as a legendary teacher. However, unbeknownst to him, Mitsuko's demise was no accident. Within Teihen High lurks a killer, dead set on making sure that Mitsuko returns to the grave.