High school loner Haruka has been busy since he and his entire class were summoned to a fantasy world. Having driven out the insurrection-causing prince, now Haruka must face the Frontier Reclamation Army--tens of thousands of soldiers--to protect the frontier. Alone. And that army isn't the Theocracy's only weapon. They're causing artificial dungeon monster breakouts to terrorize the lands, plus the final ace up their sleeve... Something powerful enough to give the former dungeon boss, Angelica, a run for her money!

When sarcastic loner Haruka gets transported with his class to another world, he's not wild about adventuring, but he wouldn't mind having some cool powers. Unfortunately, he's last in line when the magic cheat skills get divvied up, so by the time it's Haruka's turn, there are no good choices left. Now Haruka will have to take on this fantasy world the hard way--on his own, with a hodgepodge of bizarre skills! When infighting and chaos break out among his classmates, can this loner come to the rescue?

Haruka meets a group of clerics in the fantastical frontier of Omui. One of the clerics, Arianna, is actually the princess of the Theocracy. She explains the Theocracy's deep corruption, and Haruka resolves to protect her from an upcoming political purge. First, he'll send her party someplace safe--a dungeon?! Thus begins a revolutionary power-leveling training regime: the clerics are bound to get stronger than any pursuing assassins! And when Arianna is concerned about her homeland suffering under the new papal reign, Haruka has a plan in store for that too...

FIRING ON ALL FOUR CYLINDERS! Haruka reluctantly saves the day again and again, but now he wants nothing more than to go home to his cave and enjoy his loner life! But fate has grander designs in store for the hapless young lad. Word of an ancient, loot-laden dungeon rolls in, and the tantalizing allure of treasures unknown is too much for him to resist! Into the depths our loner hero goes, but he may well meet his match in the form of a being far more lonesome than he... The Dungeon Emperor!

Loner Haruka and his classmates set out for the Beast Kingdom as envoys for Diorelle amid the Theocracy-induced political turmoil. Their mission? Win the Beast Kingdom's support! But the beastfolk revere strength above all else and seem to distain the low-level Haruka. If that isn't bad enough, the strongest members of the tribe challenge Haruka to a duel!

Haruka has reunited with his classmates in the city of Omui, but as a loner through and through, it isn't long before their presence starts getting to him. An excursion to a dangerous underground dungeon gives him a much-needed reprieve...when he falls all the way to the bottom level, the domain of the legendary undead Emperor of the Labyrinth! But Haruka won't be alone for long--he'll soon be joined by a powerful skeleton knight who's somehow also a seventeen-year-old girl!

The frontier has been saved from Nallogi's advances, but Haruka's problems aren't over yet! As Haruka and his classmates delve deep into the dungeons around Omui, they encounter an invincible dungeon king, strong enough to rival Angelica herself. Meanwhile, the kingdom moves against the frontier, led by a mysterious member of the royal family. Are Haruka's cheat skills enough to escape unscathed, or is this the end for the fantasy world loner?