The monster of 1st grade, class A.

When Tarou Jimi is assigned as the homeroom teacher of class 1-A at an all girls' high school, the rest of the staff feel sorry for him. On the surface, class 1-A is full of pretty and talented girls on the cusp of adulthood. But under the pretense of grace and elegance, the girls of 1-A are akin to the spawn of the devil, known to drive all their homeroom teachers to resignation. Every teacher they have had has already been forced to quit with poorly disguised bullying and blatant blackmailing.

At the forefront of class 1-A is Momo Hananaka, a model who knows exactly how to use her charm to her advantage. As soon as she learns about Jimi, she gears up to make him regret being chosen as her newest homeroom teacher. However, Momo and the "monsters" of 1-A might be in for a surprise, as beneath Jimi's plain demeanor hides a dark past—a past that might make him nothing less of a monster himself.