WARNING: This article contains spoilers.
Heigou is the twin of Tetsu and the dark god. He takes human form by using the body of Lord Talos as a conduit.
Heigou was born from Tetsu's crystal skin when the other god grew bored and lonely. He ruled over Sudeki and its subjects alongside Tetsu until he grew greedy and decided to claim the world for himself. He banished Tetsu, and fought against Tetsu's Champions in the ensuing battle. When Heigou realised that he was on the losing side of this battle, he split the world of Sudeki into two twin worlds; Haskilia and Akloria. A thousand years passed and a prophecy foretells an Age of Unity.
Heigou's goal is to stop this prophecy from coming to pass, by preventing the worlds of Haskilia and Akloria from being merged and maintaining a segregated Sudeki.
Queen Lusica fears her own mortality, and plans to summon Heigou in exchange for his grant of eternal life. She and Lord Talos use the crystals in Elco's crystal tower machine to channel enough magical energy for the summoning. Lord Talos becomes the living embodiment of Heigou, and backs out of his side of the deal with the Queen. He promptly executes her and takes her head with him to the Void. There, he encounters a newly merged Tal, Ailish, Buki and Elco. Talos tosses the Queen's head at her daughter Ailish's feet and confronts the four new champions of Tetsu. Tal takes up the challenge.