The Mythus (ミトスの民) is a non-human race in Nayuta no Kiseki.
The Mythus originally lived alongside humanity. They shared their incredible knowledge and technology with mankind and used their Astral Power (星の力) to guide the world. They were worshipped as kins of the gods. One day, however, humans made a mistake and brought a disaster upon themselves, destroying the civilisation they had been building up and the nature they had been living among. The Mythus predicted the disaster and started preparing a plan in advance.
This plan, known as the Terra Plan (《テラ》の計画), aims to preserve the flora and fauna of the planet what would be lost during the disaster. Their ultimate aim was to revive the planet to its former glory, the Recreation of the World (再創世).