The Makai fight a secret war against the demon forces known as Horrors, evil creatures that manifest themselves through darkness to devour Humanity. On the frontlines are the Makai Knights, given the task of watching over a district and eliminating any Horrors that manifest there. GARO follows the tales of the Knights bearing the title of ‘Golden Knight Garo’, and their duty to vanquish the Horrors and protect Humanity from the darkness.

In a world separate from the humans is a place called Chou Shinkai. In this world lives super beings called Hikaribito. However, among such people are those who commit crimes. Such people are known as Kageribito. The ruler of Chou Shinkai is the Shinkai King. There are monsters in Chou Shinkai called Magii. When Magii appear in the human world, they can be seen by people with strong spiritual senses. Since ancient times, Magii have been called mononoke or youkai. Hikaribito Gou and Navi travel across Chou Shinkai in their ship, the Bunba, to deliver the Kageribito to the land of exile. But when the transport mission goes wrong, Gou must gather a team of five brave people before the 1000 soldiers arrive in 100 days.