The first planet in the Hiiro system and one of the two habitable planets, Hiiro a is officially named Norusa. The other one is Subera. The planet has an international organization called the United Nations of Norusa. It was also the first planet visited by the Youkais.
Not so long ago, the planet and Subera was formed. Quantities of water hit both planets, which made them water planets, but the bombardment of hundred of asteroids and meteors made it impossible. Thus, volcanoes and the impacts had made land, which is what Keiyu is now. However, 750 million years later, it was made to look like one of Earth's prehistoric maps due to a dark energy which can mirror planets. This was the same with Raia. After the incident, life was different due to the instant change. It did remain the same to the present time.