A young boy who died of illness is summoned to another world by 'certain spirits'. This world calls individuals with immense power, obtained after countless battles, 'Demon Lords'. Given a new life and name, Marea, by the spirits, he trains in a snowy mountain to inherit their power. However, the will of the era shapes him into a 'Demon Lord'. After a certain incident, Marea resolves to live as a 'hero to the Demon Lords'. This is the story of the man known as the 'Lord of a Hundred Demons' and the hundred Demon Lords who followed him. A book version with illustrations and new writings is available in 6 volumes from Kadokawa Books. A manga adaptation is serialized in Akita Shoten's Champion Cross. This work is also simultaneously published on Kakuyomu.