On Tailed Beasts (Bijū)

The nine tailed beasts "bijū" that the Sage of Six Paths divided from the ten-tails are roaming freely during this period of time in the ninja world. However, these ten tailed beasts tend to mind their own business in their own piece of land that's famous for the tailed beast residing in it. Every now and again, there's news of a tailed beast acting out aggressively or otherwise, which has led the people of the ninja world to fear their power and place in the natural world.

The nine tailed beasts are as followed:

Shukaku (Shukaku), more commonly known as the One-Tail (Ichibi), inhabits Kaze no Kuni, or the Land of Wind. Being a chakra entity, its influence is over both sand and wind.

Matatabi (Matatabi), more commonly known as the Two-Tails (Nibi), inhabits Kaminari no Kuni, or the Land of Lightning. Being a chakra entity, its influence is over astral fire and the undead.

Isobu (Isobu), more commonly known as the Three-Tails (Sanbi), inhabits Mizu no Kuni, or the Land of Water. Being a chakra entity, its influence is over water.

Son Gokū (Son Gokū), more commonly known as the Four-Tails (Yonbi), inhabits Tsuchi no Kuni, or the Land of Earth. Being a chakra entity, its influence is over lava.

Kokuō (Kokuō), more commonly known as the Five-Tails (Gobi), inhabits Tsuchi no Kuni, or the Land of Earth. Being a chakra entity, its known for its great physical strength, speed and maneuverability.

Saiken (Saiken), more commonly known as the Six-Tails (Rokubi), inhabits Mizu no Kuni, or the Land of Water. Being a chakra entity, its known for its influence over corrosion in the form of a liquid or a gas.

Chōmei (Chōmei), more commonly known as the Seven-Tails (Nanabi), inhabits Taki no Kuni, or the Land of Waterfalls. Being a chakra entity, its known for its powers to use insect-like techniques and has the ability to fly.

Gyūki (Gyūki), more commonly known as the Eight-Tails (Hachibi), inhabits Kaminari no Kuni, or the Land of Lightning. Being a chakra entity, its known for its power to use ink and its sway over natural disasters such as tornadoes.

Kurama (Kurama), more commonly known as the Nine-Tails (Kyūbi), inhabits Hi no Kuni, or the Land of Fire. Being a chakra entity, its known for its power to use fire, generate collosal, disastrous effects (such as shock-waves).

NOTE: The idea of sealing tailed beasts in shinobi isn't yet thought up at this point in time, however, that may very well change in the future.