Empty Void

The Ninja Village Leader is the leader and founder of the Ninja Village where Flashy Flash, Speed-o'-Sound Sonic, Gale Wind, Hellfire Flame, and many other ninjas come from. His real name is unknown; all of the ninjas from the village simply refer to the leader as "he" or "him".

Personality
Little is known about his personality, but it is safe to assume that he is a ruthless and rather despicable individual, since he is the one who started the ninja village and the atrocious regiments children are put through. He is also very arrogant, as he challenged the top S-class hero Blast to a fight and was defeated by the hero, being put in a coma for 15 years.

History
Sometime in the past, the ninja village was founded by a man regarded as the most powerful ninja to ever walk the earth. From this point on, several ninjas were trained in separate graduating classes and were sent to factories in the underworld.

Some time later, the leader of the ninja village challenged Blast and was defeated. Although Blast didn't kill him, the leader was put in a coma, and the ninja village placed him in a regeneration chamber to speed up his healing.

Ninjas Arc
After Sonic is once again defeated by Saitama and is recovering, he is approached by the Heavenly Ninja Party. This party consists of ninjas from previous graduating classes of the village, including Gale Wind and Hellfire Flame. They tell Sonic that "he" is almost awake, and reveal to Sonic their plans to kill Flashy Flash and Blast, make the leader of the ninja village their leader, and come out of the shadows to take over the world with their superior ninjutsu skills.

Powers and Abilities
While his fighting abilities have not been shown, it is safe to assume that the ninja village leader is an extremely powerful opponent. He is regarded as the most powerful ninja to ever walk the Earth by all the ninjas who graduated from the village, indicating that he clearly has abilities that are Class S level. Despite his amazing power, he was still not strong enough to defeat Blast, the highest ranking S-Class hero, and was put in a coma by him for 15 years.

Ninjutsu Master: Being considered the strongest Ninja to have ever lived, he is clearly highly skilled in Ninjutsu.