100 Rounds in the Furnace: Sensei Justin Hagen Unlocks Gold in the Iron Gauntlet Challenge

On August 1, 2026, inside the USKA Fight Sports boxing ring at the Rock Rec Center in Shavertown, Pennsylvania, the traditional spirit of Kyokushin collided with modern combat sports in a relentless trial of endurance as a day time spectacle before the USKA Muay Thai show later that evening.

The concept was simple, brutal, and unyielding: step onto the mat weighing just 167 pounds, face a continuous, rotating line of fresh, hungry fighters from every discipline imaginable, Muay Thai, Shotokan, Kyokushin, Kickboxing, and wrestling, and fight continuously for 1-minute rounds. Wraps only. No shin guards.

The goal? To reach the pinnacle of the newly forged Iron Gauntlet Title Belt System. Passing 25 rounds meant Bronze. Reaching 50 meant Silver.

100 rounds meant Gold.

When the final bell chimed, Sensei Justin Hagen hadn't just survived, he unlocked the Gold Level Title, pushing past sheer physical exhaustion to set a terrifyingly high benchmark for all future challengers.

A Crucible of Styles and Heavy Hitters

Inspired by the relentless drive of Sosai Mas Oyama and the immovable resolve of Fudo Myoo, a patron guardian of martial arts who stands unshaken amidst roaring flames, the event was governed by Modified Sweep the Leg Knock Down rules. That meant full-power strikes to the body and legs, clean sweeps, and zero head contact. Brief pauses were only earned if an opponent was swept and short water breaks were only offered at the 25, 50 & 75 round markers.

When the event commenced, Hagen was forced to weather shots from 10 heavy hitters on rotational repeat. Without weight classes, many of his opponents to fight bare knuckle. Only a few who chose to wear MMA gloves or boxing gloves as personal choices from their chosen disciplines.

• The Heavyweights: Hagen found himself trading punishing body blows and leg kicks with monstrous opponents like Andrew Sassi, a 290 lb Muay Thai striker out of Beltrante Fighting Systems, alongside seasoned 200 lb Kyokushin powerhouses Giorgi Dagargulia and Ian Ballantyne (IFK Kyokushin under Shihan Kamil Maras).

  
  

• The Technician: Georgian-born Koba Buishvili (185 lbs), bringing a dangerous mix of Kyokushin and Shotokan prowess

  
  

• The Fresh Fire: The speed and pressure were kept at a blistering pace by lighter, explosive fighters like Ian Jung, Charles Riegg, and a fresh walk-in challenger midway through the event, lightweight Muay Thai fighter Will Cavallo. Cavallo stepped up when Hagen was already deep in the trenches, delivering crisp, hard strikes to push a ragged fighter even closer to his absolute limit.

  
  

• Sabaki Challenge Legend: Entering at 250 lbs and former Sabaki Challenge fighter was Daniel Santillo, a 5th Dan Shotokan practitioner out of Old Town Martial Arts. When asked "When you find yourself in the 'pocket' taking heavy shots, what is the internal dialogue that keeps you from backing down?" to which his response was "This is fun!"

  
  

• Kyokushin Master: Shihan Chris de Wet, (6th Dan, International Karate Alliance Kyokushin Ryu), entered the ring as a powerhouse of pressure and anchored the event in deep traditional respect. As Shihan de Wet put it best: “Together we are stronger. Together we can accomplish many things.”

  
  

• The Cleaner: As Hagen reached the 100th round, his 13 year old son, Jayden Johnston-Hagen, entered the ring for the final push. Do not be fooled by his age however, an international junior Kyokushin Champion in his own right, Jayden unleashed a torrential bare knuckle hailstorm in one final push to try to take down his father, even reversing a sweep attempt as a symbolic passing of the torch to the next generation.

Forged in the Quiet Months

An accomplishment like 100 continuous rounds doesn't happen on the day of the fight; it's the quiet byproduct of months spent in the dark.

Hagen’s preparation merged ancient conditioning with modern sports science. Months of training included grueling hours in the dojo and outdoor heavy bag sessions with a bag hoisted over a tree branch, conditioning strikes against a tree trunk used as a makeshift makiwara, and lower-body development built through Sumo drills and kettlebell work.

To build the specific cardio and muscular endurance required to survive 100 different opponents, Hagen put in hundreds of sparring rounds at local hubs like Harleysville BJJ and Beltrante Fighting Systems, laying down the physical capital necessary to survive the furnace.

What kept Hagen going all this time and motivated him to pursue such a feat? The answer is simple: an intrinsic drive that transcends logic or reason. Put best in the words of Yamamamoto Tsunetomo, author of the classic book of the Samurai known as the Hagakure:

The Way of the Samurai is in desperateness. Ten men or more cannot kill such a man. Common sense will not accomplish great things. Simply become insane and desperate.”

— Yamamoto Tsunetomo (Hagakure)

What’s Next: The Iron Gauntlet Documentary & Legacy

This 100-Round Kumite wasn't just a personal test, it was the live-action blueprint for a new standard of martial arts testing and the subject of an upcoming feature-length 4K documentary.

The film, captured by Ringside Radar, will dive deep into the brutal physical preparation, the psychological dark places one enters during continuous combat, and candid interviews with the fighters who stepped up to test the iron. Every sweat-soaked round was also dedicated to real-world heroes, partnering with Vet Tix to bring active-duty service members and military veterans to the Rec Center .

Now that the blueprint has been drawn and the Gold Title unlocked, the door stands open. The Iron Gauntlet Challenge will serve as a future rite of passage for martial artists who earn their way through the Sweep the Leg circuit.

To learn more about the project, follow the production, or back the upcoming feature documentary capturing the full trial, visit the official Kickstarter campaign:

👉 Back the Iron Gauntlet 100-Round Karate Documentary on Kickstarter

You can train under Sensei Hagen at his Tetsujin Kai Dojo located with Urban Fit in Hatfield, PA. Drop by or send him a message anytime through his website HERE