The Inverted Towers are revered and feared for their potential to cause the end of the known world. So, when one of these Towers in the Kingdom of Metridium begins to rise again, the King and his royal mage quickly seek out a solution. Choosing to create intelligent homunculi, they host a summoning ritual to create homunculi with the souls of humans, but it goes wrong and now the homunculi that were to be the sword and shield of the world are scattered across it instead.

We follow Pier, one of these homunculi, as he explores a world entirely unknown to him and not only uncovers secrets hidden behind his new homunculus body, but also the secrets of the Inverted Towers and their time-lost origin.