Japanese kickboxer Tenshin Nasukawa, who aims to make history by defeating boxing superstar Floyd Mayweather Jr, claims his left-hook is like a “bolt of lightning” that will “change the world”.

The baby-faced southpaw with a blond quiff, who is only a few months out of his teens, was barely known outside his home country before the shock announcement of his New Year’s Eve fight with the unbeaten Mayweather.

But the 20-year-old from Chiba near Tokyo is considered something of a prodigy in Japanese fighting circles and began learning karate at the tender age of five.

Like Mayweather, he has never been beaten, boasting a 27-0 record as a professional kickboxer with 20 wins by knockout. He has four wins out of four in mixed martial arts.

Nasukawa won the world junior karate championship when he was a fifth grader and shifted to kickboxing a year later, according to his official website.

He made his professional kickboxing debut at the age of 16 and became bantamweight oriental rules world champion a year later.

Promoters RIZIN said that Nasukawa – or “Ninja Boy” as they dubbed him – had “become one of the most popular fighters in Japan, and perhaps the best combat sports prospect the country has ever seen.”

There are still no details as to under what rules the fight will be held – whether kicks will be allowed, for example – but Nasukawa claimed after the bout was announced he had “a punch that boxers don’t have”.

“I don’t care what the rules are. I want to be the man who changes history. I’ll do that with these fists, with one punch – just watch,” said Nasukawa.

‘Gym rat’

Even Mayweather acknowledged that Nasukawa was “an unbelievable talent”, praising his lithe, “gym rat” physique.

“He’s very special, he’s fast, he’s strong. I’m older now and when it comes to experience, I have it on my side. He has youth on his side and he’s going to bring a lot of excitement,” said the 41-year-old American.

Nasukawa now weighs 56.8 kilogrammes and is also giving four inches away in height to Mayweather, who won world titles in five different weight classes.

“Our weight class is different, but it means nothing to me,” said Nasukawa.

According to his official site, Nasukawa is good with his hands in other areas than punching, saying he is a fan of knitting and sewing – as well as indulging in traditional Japanese “sento” baths.

Despite his tender age, he published a biography last year entitled “Kakusei”, meaning “Awakening”.