What's Wrong with a Frontier Town? I'm Its Uncrowned King!

He transmigrates into a martial world set in ancient times. This world is full of danger, where human lives are worth less than grass! Outside the city, bandits and mountain brigands waylay travelers and rob them. Inside, gangs run rampant, bullying the people and extorting protection money. When the White Calamity strikes, a million barbarians march south as one, fighting to survive and battering at the passes. All life is about to be devastated in an impending catastrophe! Yet none of this has anything to do with our protagonist. He quietly hides away in his little town, surrounded by beautiful companions and living like its uncrowned king. Life is good. Bandits and defeated soldiers outside? I never leave the city! Gangs bullying the people inside? Those gangs all call me boss! A million barbarians at the pass? That sounds a little dangerous. Oh dear, looks like I have no choice but to leave my stronghold!