Becoming a Monster Fighting Master

In this strange world, humans and monsters live in peace. They have even invented a game called Monster Battle.

Anyone can use a Monster Summoning Device to summon monsters and fight.

The newly awakened Reiblood has possessed a young man from First Town, only to discover that he can't control the boy's body.

"Kid, use Monster Battle to conquer the world! You'll become the strongest Reionyx in the world!"

"Not interested."

"Fine, how about this? If you defeat your opponent, you can do whatever you want with them for an hour and spread your Reionyx genetic factors."

"Sadola, let's set off on our journey to become the strongest Reionyx!"