Night fell as Robin and Hirwa, clad in black bodysuits, quietly infiltrated Water 7's oldest underground canals. These waterways had long been cut off from the city's main system. Neglected for years, they were filled with silt and debris, but they provided perfect cover for treasure hunters.
"The structure here is unusual," Hirwa said, studying the runes on the walls. "Look at how these stone blocks are joined. This was definitely not the work of ordinary craftsmen, but a trace of ancient techniques."
Robin touched the wall and closed her eyes as though sensing something. "I can feel it... some kind of energy flow moving faintly through the walls. It feels like Moonlight Island, but older and more dormant."
They ventured deeper along the canals, avoiding the strange creatures that occasionally appeared in the water, until they finally stopped at what seemed to be a dead end. Hirwa carefully examined the wall and found a D-shaped Mark on an inconspicuous stone, nearly worn smooth by time.
"Here," Hirwa whispered. "Push this stone. There should be a mechanism."
Robin nodded and pushed the stone with force. Surprisingly, though it looked immensely heavy, it sank easily into the wall. Then, accompanied by the sound of turning gears, the wall slowly split apart, revealing a hidden passage.
"An ancient automatic mechanism," Hirwa marveled. "Even after centuries, it still works."
At the end of the passage stood a massive metal door, covered in ancient writing and symbols. Robin carefully studied the text. "This is the formal script of the Ancient Kingdom. It says, 'Knowledge is power, truth is freedom.'"
Hirwa took out the Sky Eye Badge from his robes and carefully set it into a recess in the door. The metal door emitted a low hum and slowly opened, revealing the space beyond—an expansive