After the events of Yami o Terasu Mono, Ryuga Dougai, the current Garo, is assigned to oversee matters in Line City alongside the Makai Priestess Rian. There, meeting new allies and enemies alike, the two first face a rogue Madōgu who sees humanity's destruction as the only way to end the Horror threat and then a pair of Horrors who were once Makai Order members that are intent to revive an ancient Horror.
