the four elements

"This world is not my home,the place where the four stones hold the connection to life is"
Enter the life of twins,Mizuki and Kyoto Burner as they and plunge themselves in a world where four elements exist: water, fire ,wood and earth.
The four kingdoms:
Geniviola,
shizuha
Farlon and Marìa have one thing in common their millitary force known as the Nightriders

From evil.
Mizuki and his gang
ends up saving the geniviolan princess named serena waves from an evil organization known only as the purge their goal :Hell bent on taking over the kingdoms.