Shiny_Shirogane

Klautz had lived his whole life as a ninja... as a tool.
Yet before dying he had killed all of ninjas of his clan. He had defied the ninja code and acted on his own discretion. A code he had followed his entire life.
Even in his dying moments he had chosen a harsh death.
*Whoosh*
Suddenly, Klautz opened his eyes. By some miracle, he was still alive. He then realized that he had actually gone back forty years in time.
"I will wipe out all of the ninjas from the face of HELL!" 

Join him as he fulfill his desires and his goals, all of which he wasn't able to do before.

Note: The cover isn't mine. If the owner wishes for it, I can remove it.

Shinobi From Hell

"There was also this unfair thing. The first wave starts before even all the participants can get together at one place or communicate. Well even if they did there would have been hardly any progress." Klautz lamented as he took his stance.

Dark black balls appeared out of thin air as they floated two feet above the ground. And in the very next moment, all of them fell together as they crashed with the ground making a ticking sound as if they were hollow shells.

The curled up giant spheres opened as they showcased their true forms. They turned out to be monsters who had curled up into a sphere.

No humans