Soshite Kono Sora ni Kirameku Kimi no Uta

The world is a network of artificial space colonies that have organized themselves into a nation called St. Folia, governed by the Shumal Kingdom. The kingdom's reach is fading: outlying principalities cannot sustain themselves, succession disputes fester, and ethnic conflicts exhaust the people. Princess Lumina, heir to the Shumal throne, knows none of this — she has been raised in a sheltered palace world where none of it reaches her. When her father announces she will be engaged to Laios, the influential ruler of Ibleland, Lumina refuses and slips out of the palace on her own. What she finds outside is nothing like what she was taught. Accompanied by her childhood friend Ashe, the kingdom's finest swordsman, and her young genius tutor Pelmo, she sets out to understand the world she is meant to one day rule.