Nueno Meisuke, a newly appointed teacher known by the nickname Nube, arrives at Domori High School with a sense of foreboding. Though he is a caring homeroom teacher for the troubled Class 2-3, his earnestness is often undercut by his clumsy nature. The students are far more enamored with the handsome and pretentious new teacher, Tamamo Kyosuke. However, Nube has a profound and secret interest in the school’s Seven Wonders, which draws the suspicion of his beautiful colleague, Takahashi Ritsuko. Unbeknownst to everyone, Nube is the only teacher in Japan with psychic powers capable of killing monsters, a power sealed within his demonic left hand.

The central conflict of the series begins when a student named Noriko, nicknamed Noro-chan, starts hearing a strange voice from a mirror. Feeling overlooked and struggling with her identity, Noriko becomes vulnerable to a dark presence. Sensing the evil spirit taking root in her heart, Nube secretly begins patrolling the school grounds. When Kurita Makoto, a student fascinated by the paranormal, decides to investigate the legendary Mirror of Truth as part of the school’s Seven Wonders, the students sneak into the school at night, triggering a supernatural crisis that forces Nube to reveal his powers to protect them.

The narrative follows Nube as he balances his daily duties with fighting evil spirits and monsters that prey on weak human hearts. While Nube risks his life for his students, he is often at odds with Tamamo Kyosuke, who harbors his own secrets. The series also explores Nubes relationship with his colleagues, including the skeptical Ritsuko, and introduces other supernatural beings, such as the snow spirit Yukime, who becomes involved in his life. As the season progresses, Nube confronts various urban legends and yokai, ultimately facing a major threat that ties the supernatural disturbances of Domori High School together, forcing him to fully embrace his role as the hell teacher who protects the living from the dead.