Jean Colbert

Professor Jean Colbert (ジャン・コルベール, Jan Korubēru) is a professor at the Tristain Academy of Magic. It is later revealed that he was also known as the Flame Snake (炎のヘビ, Honō no Hebi) at one point.

Background
Colbert is the former captain of the mage troops sent to burn Agnès' village years ago, and also the person who rescued her, when he found out the village was not "plagued". Ever since, he presumably adopted an anti-war attitude, and is envious when he finds out that modern Japan is not ravaged by war.

Years later, Colbert became a professor at the Tristain Academy of Magic, specifically interested in history. He has a high interest in science and peace, which are the reasons why he likes to see Saito's world one day.

Entrance Ceremony
Colbert oversees the summoning exam of the sophomores at the Academy. When Louise de la Vallière seeks permission from him to perform the ritual again after summoning a plebeian, Colbert does not allow her and states that the ritual is a sacred event, encouraging her to finish the contract with whatever she has summoned. Colbert notices the runes on the human's left hand afterwards and becomes inquisitive with it. Later that night, he becomes successful with researching about the runes on the boy's hand, leaving him shocked.

The Plebeian Familiar Spirit
Colbert consults Osmond about Saito, specifically his runes that he had researched on the previous night, believing it to be Gandálfr. Osmond states that the runes apparently exist only in legends and, given the fact that he was summoned by Louise, cites a possible connection to the lost corner of the Pentagon, namely the Void. Because of its sensitivity of the issue, Osmond orders Colbert not to speak about any of the matter to anyone.

Fouquet Strikes
During the final preparations at night on the eve of the Familiar Exhibition, Colbert assigns guards from the Vault to guard the gates. Longuevuille encounters him and shows worry on his decision, given that Fouquet is on the loose lately, particularly after the treasure in the Vault, but Colbert dismisses the idea, especially that the Royal Guard would be present should the thief opt to infiltrate the premises and because the entrance would be improbable to enter by a triangle-class mage. Later, Princess Henrietta arrives at the Academy, welcomed by the students and staff. As the Familiar Exhibition commences, Colbert officiates the event; eventually, he declares Tabitha as the winner of the event. After Fouquet strikes, Colbert and Osmond check the Vault and see a message from Fouquet, confirming her robbery.

After the incident at the Academy, Colbert calls for Louise and Tabitha to come to the headmaster's office, though Kirche and Saito tag along as well. Longuevuille briefs them on their gathered information about the thief and shows them a sketch of Fouquet, further confirmed by Louise and Tabitha. Amidst suggestions to seek help from the Palace, Osmond decides to take the matters at hand, asking help from his fellow mages who wish to take the mission in catching the thief. Not one from them are up for the challenge, except for Louise and, later, Kirche and Tabitha. Longuevuille volunteers to go with them as their guide.

Ultimately, after their mission success, Saito stays behind to talk to Colbert and Osmond about the Staff of Destruction — a rocket launcher that came from his world into Halkeginia. Osmond explains an incident from thirty years ago, where a mysterious man once saved his life from a dragon using the Staff of Destruction. Colbert comments on the complexity of the story behind the infamous weapon.

Trivia

 * In the novels, Tabitha did not cast a spell on Colbert. Instead, Kirche tricks Agnès into thinking that he is dead.
 * He is likely named after Jean-Baptiste Colbert, finance minister to Louis XIV from 1665 to 1683.