Seijo Shikkaku

Once every hundred years, an imperial election is held to avert a ruinous future. Many candidates for the throne make a pledge to the saint and compete for the throne. Despite being a descendant of the first saint, Silvia, the eldest daughter of the Holy Duchy of Bernia, is oppressed by her family and the people of the territory because she lacks magical powers. However, on the night of the saint's birthday, for some reason, the holy eye resides within her, even though she should not be qualified to be a saint.

"I'll be an experimental subject!" Silvia secretly runs out of the house, and as she runs for her life, she has a fateful encounter...!?

(Source: Shueisha, translated)