The kickboxing world is about to meet the next chapter of the Nasukawa legacy.

Ryujin Nasukawa will make his highly anticipated ONE Championship debut at The Inner Circle 23 on Friday, July 24, at the world-famous Lumpinee Stadium in Bangkok, Thailand. The 20-year-old phenom will face Thai veteran Thongpoon PK Saenchai in a strawweight kickboxing bout, streaming live on live.onefc.com in Asia primetime.

At an age when most fighters are still developing their craft, Ryujin has already captured huge titles and established himself as one of Japan’s most exciting striking stars. His arrival in ONE promises to be a momentous occasion, as the young Japanese phenom looks to announce himself on the global stage and extend the legendary Nasukawa family legacy.

Here are five things you need to know about Ryujin before he makes his ONE debut.

Ryujin Comes From Kickboxing Royalty

Ryujin is the younger brother of Tenshin Nasukawa, who was considered the greatest pound-for-pound kickboxer of this era before switching to boxing. By the end of his kickboxing career, Tenshin had compiled a remarkable 42-0 professional record, with the vast majority of his victories coming via knockout.

While Ryujin walks in his brother’s shadow, he is determined to forge his own path and create his own legacy separate from Tenshin’s accomplishments. The crucial difference between the brothers is their fighting stance: Tenshin is a southpaw genius, while Ryujin operates from an orthodox stance.

The Nasukawa family has already transformed kickboxing’s global landscape through Tenshin’s dominance and worldwide popularity. Now, Ryujin wants to take that legacy to the next level. With his debut on the global stage, the younger Nasukawa is positioning himself to make an equally significant impact on the sport in the world’s largest martial arts organization.

He Has Already Won Major Kickboxing Titles Outside ONE

Despite turning professional just four years ago in 2022, Ryujin has already captured multiple prestigious World Championships. His ascent through the professional ranks has been meteoric, with the young striker winning major titles in an incredibly compressed timeframe.

At just 18 years old, Ryujin captured the RISE Flyweight Title with an emphatic first-round stoppage of defending titleholder Riku Kazushima in 2024. This victory at such a young age announced that Ryujin was not just another prospect — he was a legitimate champ.

He also captured the inaugural ISKA K-1 World Strawweight Championship in 2025 after facing Hamada Azmani. Additionally, the Chiba native has scored impressive victories outside the major titles, including a knockout win against Petmai MC Superlek from ONE Flyweight Kickboxing World Champion “The Kicking Machine” Superlek‘s gym.

Ryujin’s Striking Arsenal Is Loaded

At the core of Ryujin’s fighting style is an exceptional striking arsenal that combines multiple dimensions of attack. The 20-year-old is known for heavy punching power that allows him to finish fights explosively, but his game extends far beyond raw knockout power.

Ryujin pairs that power with sharp combinations that overwhelm opponents and create openings for finishing techniques. His ability to string together punches with timing and precision makes him difficult to defend against, as he forces opponents to react to multiple threats simultaneously. 

Beyond his offensive prowess, Ryujin has developed sophisticated counter-striking abilities that allow him to punish opponents who over-commit to their attacks. The young Japanese striker is a complete package at strawweight. Against Thongpoon, expect Ryujin to showcase this full arsenal and test the Thai veteran’s defensive capabilities.

He Has Multi-Sport Combat Experience

Like his famous brother Tenshin, Ryujin has not limited himself exclusively to kickboxing. The young Japanese fighter has also competed in mixed martial arts, bringing additional depth to his combat sports resume.

Ryujin made his MMA debut on December 31, 2023, nearly a year after turning professional in kickboxing. In that debut, he faced Jongmin Shin and claimed a dominant victory via TKO in the second round. His ability to translate his striking skills to mixed martial arts while also defending takedowns showcased his well-rounded skill set as a combat athlete.

According to Ryujin himself during a Reddit Ask Me Anything session, he genuinely enjoyed his MMA experience and has indicated there is a possibility of him transitioning fully to mixed martial arts in the future. Whether he remains focused on kickboxing or eventually moves to the all-encompassing sport, his experience competing in both disciplines makes him a more complete fighter.

His Father Introduced Him To Martial Arts

The Nasukawa family’s commitment to martial arts runs deeper than just Tenshin and Ryujin’s professional careers. Their father, Hiroyuki Nasukawa, was the one who introduced both brothers to the martial arts lifestyle and remains instrumental in their development as fighters.

Ryujin trains at Team TEPPEN under his father’s guidance, maintaining the same gym where his brother developed into a World Champion. This family-oriented training environment has proven to be an excellent incubator for talent, as both Nasukawa brothers have thrived under Hiroyuki’s mentorship and instruction.

Now, with his ONE Championship debut on the horizon, Ryujin is poised to take the next step and cement himself as one of the most exciting strikers of his generation, continuing the legacy that his father and brother have established.

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