Rudra no Hihou

The Earth is ruled by heavenly powers, who destroy it and create it again every 4000 years, to end the live of powerful races and to let new ones appear. Many years ago, four great races dominated the Earth: the wise Danans, the beautiful Mermaids, the proud Reptiles, and the strong Giants. But those races had to give place to a newly born race: the humans. During the era of the humans, the planet's air has become filled with smog and the water dirty with pollutants. The cult of the Rudra have appeared and begun fortelling the end of the world. As the 4000 year deadline approaches, three characters each embark on their separate yet intertwined quests.