|Occupation||Teacher (formerly of class 3-3)|
Mr. Koga was a homeroom teacher for the 9th Grade Class 3.
Mr. Koga is an adult with short black hair and black eyes. He is shown wearing a white shirt with a black tie and gray pants.
In 1983, Mr. Koga was the homeroom of Class 3-3. In a last, desperate attempt to break the class, he organized a trip for two days and three nights at the inn.
After praying at the shrine, Mr. Koga declared everything would be okay and the curse had been lifted. This was not the case, however, as three more students died on the way down the mountain, before Katsumi stopped the calamity by accidentally killing the extra student. However, as the dead student was immediately forgotten by nearly everyone, it was assumed by Koga and the rest of the faculty that his plan had worked.
Because of this, in 1998 Mikami-sensei organized the same trip, hoping visiting the shrine would fix the curse. Instead, it had much the opposite effect, as two students took matters into the own hands and the inn keeper burned the inn to the ground, killing several students.