I Ended Up Raising the Seed of Evil [PA]

Astraea, the strongest swordsman in the world. One day, she realizes that she has been reincarnated as a character inside a book. And not just any side character, but the one destined to be killed by the final boss, the god of darkness. But during a hike in the mountains, she saves a young boy from assailants... only to discover he's destined to become that god of darkness. 'Fine, then! If it's comes to this, I'll...