This is the story of a kingdom.
The king has seven children.

Today is very important because heir of the throne will be decided.
He said to the children:
“A person who arrives the deepest floor of The Royal Tomb at fastest, I'll admit as the next king.”

The Royal Tomb is a cemetery that ancestors and heroes are rested. And it's a dungeon to make a trial of the adventurer's courage.

The youngest of the royal children, Prince Natri will also challenge this trial.
Can he arrive the deepest floor?