Rimuru's Big Four

Rimuru's Big Four (四天王) is made up of Rimuru's top subordinates as of the events of Monster Capital Opening Festival. He made up the group on the fly as a measure to prevent his top executives from participating in the tournament. As it stands, it's just a ceremonial post with no real meaning. Benimaru, Shion and Diablo occupy the first 3 posts – with Gobta taking the last for winning the tournament.

Trivia

 * The concept of the "Big Four" is common across Japanese media and in fantasy settings it usually refers to the four generals who have to be defeated before challenging the Demon Lord.