The Heritors of Arcadia (アルカディアの継ぎびと,Arukadia no Tsugi Bito, lit. Arcadia's Successors) is the Ending Credits song of Fire Emblem Echoes: Shadows of Valentia. It is sung by Janis Crunch in the Japanese version and by Bonnie Gordon, voice actress of Silque, in the English version.
The English version appears to be a song from Mila's perspective at the end of Echoes recounting the events of the story. It references a Jasper Lion who will lead the people into a promised land and a better future. The song alludes that, despite Mila's death, she will still be watching over the humans and be there to protect them in their time of need - likely referencing the importance of the Mila Tree as a location in Fire Emblem Awakening.
In an interview with Bonnie Gordon, she was not planned originally to be the singer. She auditioned when she overheard the Sound Engineer and Director mentioning that they were looking for someone to perform the song.
The octave change between the Japanese and English versions is due to Bonnie Gordon's slightly lower vocal range.
Fledgling Warriors: The Astral Temple - Band of Bandages - Wretches and Riches Undaunted Heroes: Wealth Before Health - The Inner Sanctum - Lords of the Grave Lost Altars: Altar of the Destrier, Altar of the Titan, Altar of the Skylord, Altar of the Sorceress, Altar of the Faerie, Altar of the Ogre, Altar of the Marksman, Altar of the Savant, Altar of the King, Altar of the Queen Rise of the Deliverance: Battle of Zofia Harbor - Outpost Rescue - Flight from the Ruins - Siege of Zofia Castle Cipher Companions: Cipher Legends I, Cipher Legends II