Waruiotoko 
Only the Villainous Lord Wields the Power to Level Up: Volume 4 [EPUB ebook] 

Having driven off the Royal Naruyan Army, Erhin brings his troops and people with him as he sets up a new base of operations in the Bertaquin Domain of the former Brijit Kingdom. As he takes this first step towards declaring independence, he turns his eyes toward the vast sea around Brijit. Erhin hopes to build a fleet and establish maritime trade, but the neighboring Luaranz Kingdom has him massively outgunned at sea—and if history goes like it did in the game, then a coup d’état is about to turn them into a military dictatorship. What will happen when Erhin tries to stop it?