Ootsuki-sensei

The hot-blooded head of class 5-1 of Doumori Elementary, Ōtsuki-sensei (大月先生) is another exorcist/teacher combination. However, unlike Nūbē, he believes that all phenomenon are a result of plasma, not spiritual power. These beliefs lead to the two teachers consistently feuding over what is the true nature of the many problems that persist in and around the school; while the students in both classes also face off due to the loyalties to their home-teacher's beliefs. Using his own scientific knowhow and research, he uses several devices and inventions that allow him to research and take out any of these threats. (sort of similar to the scientific research and inventions done in Ghostbusters).

Although Ootsuki-sensei appears a couple prominent times early on, he merely fades into the background as the manga goes on. (Source: Wikipedia)