Four childhood friends who grew up in a village near the demon king's castle.

We were all in the S-class party in just three years.
　
When we were little, each of us had a dream.
Isaac yearning to be the strongest swordsman.
Emmy to be the strongest wizard ever.
Kara, who wants to heal people from any kind of injury.

Each of their dreams were becoming a reality, and I hoped to support them all and make them stronger. To do so, I was willing to do any chore.

I was carrying luggage, scouting, mapping, cooking, blessing equipment, walling, cleaning, sewing ...... and doing all kinds of chores, but I was fired when word got out that a brave man was going to join the group.

There are plenty of replacements.
Despite being told this, he goes to explore the last dungeon.

But when the hero actually leaves, he finds himself in .......

This is the story of the hero who was abandoned by his childhood friends, who borrowed the power of the holy beasts and strengthened them to become the strongest.

You will discover the true horror of the Holy Beast Master.