The Sewers of the Demon Lord Castle
As soon as the artificial sun of Under Barkus rose, Neromeltia and Lusteria left the vast cavern behind. The previous evening, Crawford had planned a grand celebration for the Demon Lord's resurrection, but since Neromeltia and Lusteria had remained in the hot springs until nightfall, the schedule had to be canceled. Thus, at dawn he had gathered the residents to prepare at least a modest greeting, yet Neromeltia declined and promised to return by evening so they could hold a proper feast then. With that, the two set off in haste, using flight magic to cross Barkus Volcano. Once the altitude issue was resolved, a straight path offered the fastest route to the Demon Lord Castle, and for two beings whose magical prowess ranked among the highest, the height posed no obstacle whatsoever.
Before long they reached the vicinity of the Demon Lord Castle and descended at the upper reaches of the river that ran through it. The river's name was Astar's Tears. True to its name, it once carried clear, pristine water. Defying the iron-rich, toxic environment of Hemonigent, the river remained transparent because vast quantities of groundwater filtered through the granite layers of Barkus Volcano before gushing forth. It was truly the lifeblood of the Demon Lord Castle, a fitting tribute to the tears shed by the earth mother Astar.
“From here we’ll have to dive and swim in.”
“But the water was so clear just moments ago……”
Now Astar's Tears reeked with a nose-stinging stench, its surface choked with thick green algae and sluggish sewage. Even after a thousand years the source still produced pure water, yet once the streams converged into a proper river, pollutants and toxins accumulated on the surrounding ground washed in with every rainfall, rotting the flow. Seeing the river that had once supplied the Demon Lord Castle’s drinking water reduced to this festering ruin pained Neromeltia deeply. The thought of plunging into that viscous, polluted water only made the reality more repulsive.
“……Could we perhaps compromise with reality and just fly above the surface……?”
“…I would very much prefer that……”
Protective magic could have let them move underwater without getting wet, but neither the Demon Lord nor her secretary wished to enter water so black they could not see a hand’s breadth ahead. In the end they flew as low as possible without touching the surface. They needed to minimize the risk of detection—after all, the humans might have left traps or devices inside the castle—and following the river’s course underground was the safest way to do so.
“Eeeek!! I’m so glad we didn’t go in the water!!!”
“Y-yes…… it really is……”
Flying just above the surface gave them a clear view of the river’s contents, and the sight was nothing short of horrific. What appeared to be sludge worms writhed in the depths, yet these creatures had mutated to grotesque sizes—nearly three times the height of an adult human. Their black silhouettes swarmed through the water, thriving on the concentrated pollutants. Had the two attempted to swim, they would have been surrounded by the repulsive mass. Lusteria, who had never possessed any immunity to disgusting things, trembled violently as she flew, looking ready to burst into tears at the slightest touch. Neromeltia was far more resilient to filth and revulsion, yet even she found it difficult to remain impassive; her brows furrowed and open disgust showed on her face.
Long, massive silhouettes twisted violently beneath the algae-choked surface. It was a scene she wished she could erase even from memory, lest it haunt her dreams. Doing their best to ignore the nightmare below, Neromeltia and Lusteria reached the intake of the aqueduct beneath the castle walls and slipped inside.
“Air Barrier!”
The moment they entered, Neromeltia sensed something amiss and summoned a magical veil that sealed off the aqueduct’s atmosphere. The spell was not meant for direct defense, so it could brush against external objects, but it completely blocked air and any floating particles. Originally intended for use after diving, it allowed free breathing even underwater. She had not expected to need it while flying above the surface, yet the instant they entered the aqueduct she cast it without hesitation.
“Is something wrong……?”
“The place is filled with gas. No reason to breathe this polluted air when we don’t have to.”
The decaying river had apparently filled the sealed aqueduct with noxious fumes. The two landed on the walkway inside and advanced slowly under the protection of the barrier.
“Light.”
“Just in case, I should warn you—avoid anything that might ignite a flame. Understood?”
“Of course, Master! I am the Demon Lord’s personal secretary, after all.”
“Hehehe…… I’m so fortunate to have such a clever secretary.”
Neromeltia voiced her concern to Lusteria, who had summoned an orb of light to illuminate the way. When the succubus gave her bold yet adorable reply, Neromeltia could not help but laugh. She gently patted her secretary’s head, then began navigating the complex aqueduct passages from memory. At occasional forks she paused briefly, yet she chose her routes with confidence, and every choice proved correct.
“Wow…… How do you remember the layout of a place like this so perfectly?”
“I memorized it during the renovations of the Demon Lord Castle’s aqueduct.”
“Still…… that was over a thousand years ago!”
“A Demon Lord with such a clever secretary ought to manage at least this much, don’t you think?”
“Hmph…… Are you teasing me?”
Despite her sulky tone, Lusteria stepped closer and wrapped her arms around Neromeltia’s. Such unreserved affection would never have appeared in the Lusteria of a thousand years ago, and the sight warmed the Demon Lord’s heart. After the passionate night they had shared the previous day, Lusteria seemed far more honest with her feelings and freer in expressing herself. The way she now approached Neromeltia without reserve, openly showing her affection, was the honest result of that long evening.
Even while walking through the dark aqueduct tunnel with filthy water flowing right beside them, having her pretty, adorable secretary clinging so closely made Neromeltia feel happy enough to forget the unpleasant surroundings entirely. After some time, Neromeltia stopped at a fork. One passage continued straight with the current; the other branched sideways and descended underground, its walkway turning into stairs.
“If we go down here, we’ll reach the sewers. That’s our destination.”
“Can’t we just keep going straight……? The aqueduct was already filthy enough; I can’t even imagine what the sewers must be like……”
“If we continue through the aqueduct we’ll emerge right in the middle of the Demon Lord Castle and expose ourselves from every side. It would be no different from simply flying over the walls.”
“Hnnnng……”
Already terrified before they even entered the sewers, Lusteria trembled as though she might start crying at any moment. Neromeltia felt much the same; the mere thought filled her with revulsion. If the aqueduct was this bad, how much worse would the sewers—where all the waste was collected—be? The very idea was beyond imagining. Yet they chose the sewers to avoid potential dangers. After a thousand years, they had no idea how far human technology had advanced or what schemes the dragons might have prepared. With no reliable information, caution was essential. They intended to scout the castle via the most discreet and safest route possible.
“Lust, don’t worry so much. In the old days when many residents lived here, the sewers were always full of waste, but now the castle has been a deserted ruin for a long time. With so many branching sections, far less water flows through, so it might actually be cleaner than this.”
“But……”
Lusteria’s entire body screamed that she did not want to go, yet when her master took her hand and gently led her forward, she had no choice but to follow. Though her heart longed to flee, her trust in Neromeltia was absolute, so she surrendered herself to that guiding hand and obediently descended the stairs. Ahead of them lay only pitch-black darkness, and in the midst of the loud rushing water, only the sound of their footsteps echoed through the tunnel.