Heavenly Ninja Party

Known also as the Tenninto, the Heavenly Ninja Party brings together twenty-one ninja who all graduated from the Ninja Village across different classes. Their instructors had forbidden any brotherly ties and ordered graduates to kill one another on sight, yet these fighters defied that decree and joined forces, bonded by shared conviction. What they built was an elite squad of assassins gathered from generation upon generation of the village's alumni.

Their ambitions ran in stages. First they meant to murder Flashy Flash, whom they loathed for razing the village, then to crown the man they called That Man as their leader so he could publicly put the aging Blast to death. Once both were gone, they intended to step out of the shadows and claim the world through their unrivaled ninjutsu. In the webcomic, however, the entire party was slaughtered by Speed-o'-Sound Sonic and Flashy Flash.

While Sonic recovered from yet another loss to Saitama, the Tenninto approached him, their number including Gale Wind and Hellfire Flame. They laid out their scheme and pressed him to bait Flash into an ambush, warning that betrayal meant death. Sonic seemed to comply, drawing Flash to a lonely spot where the two dueled. Impressed by Sonic's improvement, Flash knocked him aside with his Flash Kicks, at which the ninjas swarmed in together. Flash recognized them at once, and Sonic, refusing their aid, struck one of them and sided with his rival. The pair fought the group until Blast appeared to end the senseless killing, brushing the whole party aside without taking a single life.

Blast then teleported everyone to Sonic's hideout, where they found Saitama beside a human-shaped crater, all that remained of the Ninja Village leader he had beaten off-screen. The Tenninto charged in disbelief and were flattened just as easily. A rift then split open and disgorged Byakko and Genbu, guardian beasts of God, who leveled city blocks until Blast's barrier shielded everyone. Freed from God's control by Saitama's earlier blow, Empty Void joined Blast to drive the beasts back. Void, their long-awaited leader, apologized and left to rejoin the fight against God, leaving the ninjas adrift. They settled on begging Saitama to lead them instead, an offer he flatly refused, and afterward they kept pestering him at his apartment and even trailed him on shopping trips.

Empty Void, addressed reverently as That Man, was the leader the group longed to serve. Among the twenty-one ninja stood notable figures such as Gale Wind, Hellfire Flame, and Violent Force, alongside members like Balanced Equilibrium, Ballistic Bullet, Chaotic Mayhem, Freezing Ice, and Illusory Phantom, each bearing an elaborate two-word name. In the original webcomic, the group's name reversed its first two kanji, reading instead as Nintento.