The source was the Dragon's Nest at the top of the castle.
「The third day of the Sun's slumber.」
From that day on, the entirety of Black Stone Castle transformed into a gigantic, slowly heating oven.
At first, it was only the Dragon's Nest at the peak of Black Stone Castle.
Then, the heat spread to the entire castle.
The Knights discovered that the stone bricks of Black Stone Castle had grown warm. When they rested their hands on the battlements, they could feel a distinct heat.
By the fourth day, this warmth had become scalding hot.
The commoners responsible for cooling the castle had to wear soaked, thick-soled boots just to walk on the upper levels.
