The World's Least Interesting Master Swordsman

Sansui Shirokuro is a young guy with an old man's name, which ends up landing him in tragic circumstances when God snuffs out his life candle after mistaking him for a geezer whose time has passed. Now reincarnated into a fantasy world, Sansui is one of the Immortals, capable of immense power... as long as he's willing to put centuries of work into achieving it. One day, after five hundred years of swinging his sword, his monotonous existence is upended entirely by the appearance of a little baby. His master sends him out into the world to raise the child, and it's there that he meets a haughty young noblewoman and her tomboyish bodyguard. His fighting style may be bland and unpretentious, but the fast-paced mortal world is about to find out just how good even the most hopeless swordsman can get with half a millennium of practice behind him!

Master Suiboku's given Sansui his blessing, so in addition to guarding his mistress, Lady Douve, he's now offering instruction in swordsmanship. Not only is he teaching his fellow Japanese transferee Saiga and the foreign prince Tahlan, but he's somehow found himself teaching the city's ne'er-do-wells and the Royal Guard. Meanwhile, House Caputo, a Great House of the Arcana Kingdom, is fighting a war with the Kingdom's neighboring nation. Evidently, the army invading the Caputo lands is equipped with cheat items, but House Caputo's got a cheat of their own up their sleeve.

A young girl is caught up in the whims of fate! Just as the new government of the Domino Republic is about to make peace with Arcana, it comes to light that Sansui’s adopted daughter Lain is the last member of the old Imperial House, turning everything on its head. The nobles attempting to restore their former place in Domino scheme and plot to use Lain as a figurehead, while the leader of the Republic puts in motion plans to wipe out the last of the Imperial House’s bloodline... Lain is in danger! Can an uninteresting swordsman keep his daughter safe from these threats?

With the peace treaty with the Domino Republic in place, Lain's safety is all but assured, but life in the mortal world is one new conflict after another. A new challenger seeking to be the world's strongest appears: the mystery girl, Ran. This talented wild child has a more complicated history than anyone would ever have expected. Does might truly make right? Conflicting values collide and fates intertwine in this new chapter of a tale that explores the meaning of strength.

"I've spent three thousand years preparing to kill you--" Fukei has plunged the Kingdom into darkness using storm clouds under his command. An Immortal who has spent millennia training to defeat Suiboku, Fukei commands the heavens and earth and is nigh unkillable due to his Immortal Arts. Even wielding the power of the Legendary Sword Eckesachs, Saiga can do little against this overwhelming force. As Fukei threatens to destroy the Arcana Kingdom, Suiboku returns to the mortal world after thousands of years to save his apprentice's students and to apologize to Fukei. Apprentices who trained as brothers now face off, marshaling centuries of skill and power in a tragic and bitter fight to the death.

The battle for the world’s most eligible bachelor begins! Warrior princesses attack to prevent Magyan’s Prince Charming from marrying abroad! Their target? The legendary spoiled noblewoman, Douve Sepaeda! Magyan Tahlan is a man who epitomizes royal virtue. He possesses the elegance of a perfect prince, the strength of a perfect warrior, and the character of a perfect man. He is blessed with abundant talent, lacking only one thing: the ability to use Spirit Summoning. The prince who everyone had regretfully watched leave his homeland has returned, fiancé on his arm! But his timing couldn’t be worse - he’s arrived amid rumors the current king is on his deathbed! The ambitions and desires of the women who would do anything to put Tahlan on the throne have thus been unleashed. You really do leave broken hearts in your wake, don’t you, Tahlan? To think that such a man is all mine...how lovely!

The fourth time’s the charm! Saiga has lost three times and promised never to fight Sansui again, but with a reason to fight Sansui again, the two agree to fight in a flashy duel! Mizu Saiga is blessed with the ability to use all types of Rare Arts and has three cute fiances. It had appeared like the start of his Isekai Harem Cheat Life, but he had been brought down three times by the most simple attacks and took serious damage to his pride each time. A little effort isn’t enough to catch up to an Immortal who had trained for five hundred years. In order to fulfill the role expected of him, Saiga resolves to fight the greatest swordsman once again. Meanwhile, with his return to Arcana, Sansui receives news that Blois is giving birth!!! Hey, Papa, when are you marrying Mama Blois?

With the strongest swordsman around, the kingdom of Sepaeda has nothing to fear. If his master wills retribution, then he will deliver it. Douve and Tahlan, Happine and Saiga, Setenve and Ukyou... All three couples are set to have a beautiful wedding ceremony together. And thanks to the otherworldly arrivals, Arcana has been developing by leaps and bounds. This rapid growth, however, has its neighboring nations on edge. They’re afraid, awestruck, anxious, and above all, envious. Blinded by jealousy, they insult Tahlan personally. Sepaeda’s young leader immediately leaps to his defense—and he has no plans to keep things civil!