Rijichou

The chairman of the school, named Saitō Tatsugoro, is also a spirit, who can be summoned along with the others. He instructs the three members of the Holy Student Council to gather the badges for him, thus starting the series. He collects haunted artifacts from all over the world, thus continually increasing the number of ghosts that inhabit the halls. His badge color is dark blue.

(Source: Wikipedia)