A Terrible Day in Mistalore Defense Nation's History, Blackened Sky Day

The Vice Fortress Master's mind briefly flashed with horrifying memories of that colossal beast—the one that reaped the lives of hundreds of Nightmare Slayers and his… only brother.

That terrifying, unimaginably powerful beast—one so strong that none could stand against it on that fateful day.

Even with his older brother's valiant sacrifice, the most that the self-implosion of his Inner Slayer Dimension and Slayer Weapons had been able to accomplish was scaring the |Abyss Prowler| away. Shortly after, the East Fortress Master arrived, but by then, the 6th Stage 2nd Class Slayer—the last Vice Fortress Master—had nothing but his ashes remaining.

That day was ten years ago—the day when the East Frontier had nearly been overrun by a record-breaking Nightmare wave. The day known as Blackened Sky Day.