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.

As Sakura drowns in the murky darkness of the sins she has committed, Shirou’s vow to protect her at all costs leads him into a raging battle to put an end to the Holy Grail War. Will Shirou’s wish reach Sakura even as he challenges fate itself in a desperate battle against the rising tide?