Private Tutor to the Duke’s Daughter: Volume 13 by Riku Nanano

Three months have passed since the battle for the city of water. As winter nears the royal capital, Allen settles back into his old routine, tutoring the kingdom’s best and brightest while overseeing the company that bears his name—until a draconic prophecy yanks him into the cutthroat world of court politics once again. His path to curing a student’s magical ailment leads through the Sealed Archive, home to the kingdom’s most closely guarded secrets. But Allen’s old enemy, Head Court Sorcerer Gardner, holds the keys. To overcome aristocratic prejudice and fulfill the draconic prophecy, Allen will need something he’s always avoided: an official post. And as it happens, the newly minted Crown Princess Cheryl is in the market for an investigator. His first case? The deaths of another student’s parents and the plague they tried to fight eleven years ago.