Ys Chronicles+: Ancient Ys Vanished - Omen part 5: Dark Fact (Ys I finale)
Adol frees Reah from the tower, and she gives him a monocle that allows him to read the Books of Ys. With this and a the Blue Amulet from Luta Gemma, Adol faces off against the demon lord Dark Fact.
And here's a "dark fact" for you. The final boss's movement speed is tied to the framerate, so this was WAY harder for me than it was supposed to be.
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