In a world where the faith of the Old Ones, ancient and faceless gods residing in the green wood, once thrived among the First Men and the Children of the Forest, a shift occurred with the Andal Invasion. The Faith of the Seven gained prominence, leading to the destruction of weirwoods in the southern realms, except for the Isle of Faces guarded by green men. However, in the North, the faith in the Old Ones persisted, with every castle maintaining a Godswood and a heart tree adorned with mysterious faces.

Unlike other mortal gods, the identity of the Old Ones remained elusive, represented only by weirwood trees, sometimes resembling a horned deity. The rulers of the First Men, instead of adorning themselves with precious helms, chose antler helms, considering them divine symbols connecting to their bloodline origins.

Enter Jay, who, after a reincarnation, unexpectedly becomes the God of Life, Xerneas, inadvertently revitalizing the faith in the Old Ones. This sets the stage for a story exploring the clash of ancient beliefs, the resurgence of a forgotten faith, and the mystical journey of a Pokémon deity reborn in a world torn between dead and living.