The territory of Duke Rafael lay on the western edge of the Luying Empire, about half a month's journey by steam ferry.
It was one of the most flourishing territories of the Empire.
Further west, several days' journey across a vast sea, there lay a place not marked on maps known as "Black Castle Reef."
Atop the reef was a castle with a towering lighthouse.
But inside the castle lived no ordinary residents, only a secret guard unit loyal to Duke Rafael.
This was purely a military fortress.
Little known to outsiders.
Recently, the conflict between the Luying Empire and the Mafa Mechanical Empire on the East Coast had intensified, prompting many lords to call up military forces to join the fight.
The major nobles' withdrawal of troops from their territories also provided opportunities for pirates.
A fleet belonging to a pirate leader known as the "Northern Sea Overlord," Oleg J. Popov, was active near the territories of Duke Rafael, raiding passing merchant ships.