In Another World With My Smartphone: Volume 5 by Patora Fuyuhara

The newly-crowned 16-year-old Grand Duke of Brunhild, Mochizuki Touya, is just starting to get the hang of managing a nation. What better way to christen his Duchy than to host a party with all the other royals in the region? Laughter! Fun! Pinball! But it's not all fun and games, Touya's search to uncover the truth behind the Phrase and Babylon bring him to the depths of the darkest forests, and the caps of the snowiest mountains. Not only that, but new territory means new responsibilities, and soon enough the eyes of the Vatican fall upon him. “Blasphemy!” they scream, “God is no old man, he is a magnificent being of light!” How will Touya react when even the Pope challenges the honor of the old man that gave him a new lease on life. The bells toll for a riveting tale of swords, sorcery, and... savage tribals?!