Baron Kaidou

He is the headmaster of Root Gakuen High School. Throughout the series, there are very few things revealed about him, but his connection to the P.O.G. has been hinted on several occasions. In the ninth episode, it is revealed that Baron is the section-chief of Section Φ, a section within the P.O.G. wiht its own jurisdiction. He has opposed the new direction of the P.O.G. to turn puzzles into murderous threats, with no intention of letting the Solver survive. This was his motive for bringing Souji Jikugawa in his section and guide Kaito and his friends to the Puzzle of God.

Baron was also the one who brought Kaito to Root Gakuen High School and it is hinted in several flashbacks that he was involved in Kaitos past. He was later arrested by the POG for disobeying their orders.