Wolf & Parchment: New Theory Spice & Wolf, Vol. 9 (light novel) — Isuna Hasekura

Col has put an end to the battle over textbooks in Aquent and given Rutia a new purpose. With the printing of the vernacular scripture progressing nicely, it's time he prepared for the upcoming ecumenical council, where the clergy of the world will gather. To stand his own in the theological debates that are sure to occur, however, he will need to find as many allies as he can. That's why this is the worst possible time to start hearing rumors of another person claiming to be the Twilight Cardinal. Unfortunately, Col's constant humility backfires, making it surprisingly hard for him to prove his own identity. What is he to do...?