Agarest begins with a hero who was given the difficult task of defeating an Archdemon at birth. Society revolves around the myth of Yiris, known as the Sacred Princess, who blessed the world and fell in love with humans. Died for her love, she was punished by the heavenly creator. Soon after, an Archdemon appeared, and Yiris’s lover promised to destroy the evil Archdemon with the infamous rainbow sword “Ciel’s Blade”.
The hero, or Chosen One, is entrusted with producing an heir who can finally put an end to the Archdemon once and for all.