There weren't any introductions.
The Emperor just took a good glance on Reigner and his family, then his lips parted. It was time to spit out the truth about what happened to the 'black hole' worlds after the dungeon's appearance.
And since he knew about the dungeon, the emperor knew literally everything.
That was why Reigner urged him with his narrowed eyes!
"There are low, medium and high worlds..."
"I know it."
"Our low world has been connected with other two."
The situation was too severe for the low world's people. They became slaves of the high world people that were coming here frequently though the medium world. At the beginning, no one knew why would such worlds suddenly get connected.
It was joyful for emperors and kings, but the gap between the worlds quickly got exposed.