In the very distant future, long after the extinction of humanity, there live immortal beings known as "Souls," born of Mana and ANIMA -- formless spirits that dwell within humanity's many Artifacts. They have populated the world formerly known as Earth, now Eden, and have been living in relative peace for many centuries... Until 50 years ago when massive portals containing monster outbreaks known as Gates started opening above the skies all around the world, all the while destroying homes and tormenting powerless Souls born from weaker Artifacts.

As the assault escalates to an attack on the Kingdom of Solrey's capital of Elnath, Queen Yuria and Mephistopheles, an Artificial Soul created by humanity to pilot one of its nine arks, undertake a risky ritual to summon a hero from another world -- one that would help the Souls tap into their latent powers and lead them to victory. This hero -- The Savior -- is you, a normal human boy from an alternate modern-day Earth...

This is your story, alongside the girls who live forever.