Currently watching Kiba.
For those of you who don't know about it, it's about this guy named Zed who is rather mischievous. Then one day he stumbles upon a portal and get's transported to another world.

Then blah blah blah. He finds out that he has a spirit and not just any spirit, a key spirit.
Spirits come out when a ball is thrown. The ball contains the spirit. Spirits are physical, can fight, fly etc.

Nice shiz.