Arcane Gear

In ancient times an unknown entity only known as Alpha Zeroth, rampaged across the land of Astraea, when hope was nearly lost the planet itself called out to a priestess to gather 14 people with a pure soul to defend the planet, those warriors were granted power to fight back against the monster, which manifested physically into large magic armors.

Nearly 1000 years later, a young mechanic finds a girl washed ashore in the river, two days after finding a strange green crystal in some desert ruins, could both findings be connected?