Konnichiwa Tetsunihon-san!
You only add a Kanji that means water, fire, wood, metal, and wind on their name.
An instance...
water, "Misui". "Mi" means god, "Sui" means water.
fire, "Rekka". "Re" means burst, "Ka" means fire.
wood, "Taiki". "Tai" means big, "Ki" means wood.
metal, "Tetsuo". "Tetsu" means metal, "O" means man.
wind, "Fuuka". "Fuu" means wind, "Ka" means scent.
NANGI