It's the world where people should have an Inner Animal... An animela which protect them at needed times, show others about their domination, making the below ones to gave the respect they need. The Inner Animals are stated as "Below", "Normal", "Royalty", "Rare" ranks. Inner Animals will be summoned by the tattoo of elsewhere they are on their owner's body and each has a different tattoo mark. Sano Manjiro aka known as Invincible Mikey or Mikey had a Royalty. A Lion... Yet his friends like were in other different ranks. But rare... was the greatest..