“You’re over the hill, old man.”
With those words, the swordsman Kenneth is unceremoniously kicked out of his S-rank adventurer party.

What they don’t know is that Kenneth’s true identity is the legendary “Ultimate Idle Master,” known only to a select few. To him, party adventuring was never more than a way to kill time.

In search of a new cure for his boredom, Kenneth sets his sights on the uncharted Labyrinth of the Gods, a dungeon said to be impossible for mortals to conquer. Along the way, he teams up with Lily, a gunslinger, and Karen, a skilled mage. With his off-the-charts swordsmanship, Kenneth proceeds to overwhelm the labyrinth, dominating even the gods who rule it…!!

Thus begins the ultimate heroic tale of an absurdly powerful yet perpetually bored middle-aged swordsman and the beautiful girls who join him!