"Eternal Night Great Wall: We Can Never Repay Our Lord's Kindness!"
The Red Moon rose, and power tipped toward the darkness.
Vampires awoke beneath the Red Moon, werewolves lost control completely, and armies of other races swept toward human civilization like a tide.
To preserve a foothold, humanity lit the Sacred Flame, using hundreds, even thousands of frontline territories as anchor points to build a defensive line from their own flesh and blood: the Eternal Night Great Wall.
In this age, Shien, the illegitimate son of an Earl, was granted the title of Long Night Lord.
He inherited a territory on the Eternal Night Great Wall that was on the brink of collapse, and everyone believed he would not survive the year.
But at that desperate moment, his cheat, the [Gratitude Codex], activated.
It recorded every kindness Shien bestowed on others and transformed their gratitude into power.
With it, Shien selected talented people, copied skills, developed production, expanded his armaments, and advanced technology...
And so, when the Red Moon rose again, the walls were lined with people unwilling to lose it all again.
They said, "We can never repay our lord's kindness!"