After losing both of her parents in an accident, Arbell is left with a massive debt and finds work as a servant at the House of Aterna. Marua, the only son of the House of Aterna-the wealthiest and most prestigious family on the planet Enkenua-possesses Mana, a divine source not meant for humans. As a "Mana User," he is preparing for the "Trial of the Gods" to become the planet's guardian. According to the rules of the House of Aterna, Marua must father a child before the summoning, as there is a risk he may never return from the divine trial. Can Arbell, who dreams of joining the Space Defense Force, and Marua, bound by his family's tradition, hold onto the threads of fate that connect them?