In Another World With My Smartphone: Volume 9 by Patora Fuyuhara

Mochizuki Touya continues his work as grand duke of Brunhild. He's the proud inheritor of the (almost) complete Babylon Islands, the mighty master of the Frame Gear Mechs, and a slowly flowering bud of divine power, but that doesn't mean he has any room to relax! The time has come for answers! A new threat emerges within the Roadmare Union! But can Touya convince the mighty doge that his Frame Gears are the right method to deal with the oncoming danger? Just who is the enigmatic Ende, and what does he have to do with the crystal creatures that so recklessly bring the world closer to despair? Just what is the secret of Touya's divinity? Put on your thinking caps for a tale of swords, sorcery, and custom-built mechatronics!