A clear and melodious whistle resounded in the subterranean world. This was the horn of war.

The hissing sound came from Zero's mouth. As he let out a clear whistle, the eight air-energy stone on his body lit up with a dazzling light, pushing the power that was already at the peak of its strength up by another small step. However, it was this small step that caused the Zero Power to increase, turning the tornado from before into a violent thundercloud that extended across the ...