A continuation of the epic adventure of plucky Riko and Reg who are joined by their new friend Nanachi. Together they descend into the Abyss' treacherous fifth layer, the Sea of Corpses, and encounter the mysterious Bondrewd, a legendary White Whistle whose shadow looms over Nanachi's troubled past. Bondrewd is ingratiatingly hospitable, but the brave adventurers know things are not always as they seem in the enigmatic Abyss.
One morning, the high school student Takashi Komuro enjoys the silence at school when he's suddenly interrupted by strange noises and a shaky-legged person who tries to enter the school grounds. Subsequently, several teachers come to the school gate to shoo the person away. All of a sudden, a teacher is bitten by the person and within seconds the school campus becomes a place of violence, blood, death and undead zombies. Takashi, shocked by the scenery, runs for his life to save his schoolmates and childhood love, Rei Miyamoto. The struggle for survival has just begun…
