Chou Nankan Dungeon de 10-mannen Shugyou shita Kekka, Sekai Saikyou ni: Saijaku Munou no Gekokujou

"The Most Incompetent in This World"—it was the gift Kai Heineman received from the Divine Oracle when he was thirteen years old. Due to that gift, his physical abilities plummeted. His growth rate became the lowest in the world. Yes, the gift was supposed to make him a target of everyone's mockery and pity. However, this gift had something that no other gift had, limitless growth.

Moreover, by chains of unfortunate coincidence, Kai Heineman ended up being trapped in the worst, nightmarish dungeon. The dungeon disconnected him from the passage of time in the outside world. This allowed him to train for a really long time while just a moment passed in the outside world, without ageing even a single day. This chain of misfortunate events led to the birth of the most powerful supreme being in the world.

This is the tale of the loner, whose common sense got so distorted after he spent too much time talking with his own sword that he brought out the subordinates he had subjugated in the dungeon to wreak havoc in the outside world.

(Source: Shousetsuka ni Narou, translated)