long long ago, HUMANS and MONSTERS lived together on the surface in unison.  All was well for both of their kinds. 

But, a war broke out. A war between the HUMANS and the MONSTERS.

The war was great and horrid. But alas, one of the two races had to be the successor. The HUMANS overthrew the MONSTERS in the end.

The MONSTERS were rushed and sealed into MOUNT EBOTT by the HUMANS.

Since then, a legend of the mountain was formed. those who go up there NEVER RETURNED.

The only way for MONSTERS to escape the barrier trapping them underground is that they needed seven HUMAN souls. After years of struggle underground, the MONSTERS have collected six HUMAN souls. Freedom was near.

YOU, a HUMAN, adventures up the mountain. And end up falling into a hole that leads to the UNDERGROUND. The MONSTERS will fight for the final soul they need.YOUR SOUL.