(Reuters) - ONEFC lightweight champion Kotetsu Boku is tired of living in Shinya Aoki's shadow, watching the Japanese submission specialist steal top billing on fight cards and dominating headlines at mixed martial arts (MMA) events all over Asia.

Boku believes the time is right to change all that.

"Yes Aoki has been the bigger star. Even when I won my lightweight championship he was the main event," Boku told Reuters in an interview ahead of their ONE Fighting Championship title bout on April 5 in Singapore.

"Leading up to this fight, he is seen as the favourite and I'm the underdog - even though I'm champion.

"But I embrace the underdog role and I will once again, proving all the doubters wrong. Beating Aoki will be the biggest win of my career and I'm ready for it."

While Boku is a relatively unknown quantity outside of Japan, Aoki has built a solid reputation as one of the world's top lightweights.

He has gone up against some of the biggest names in the division including Eddie Alvarez and Gilbert Melendez and fought on international promotions Bellator and Strikeforce.

Boku, who made his MMA debut in 2001, fought for the first time outside Japan in October last year when he beat heavily fancied Brazilian Zorobabel Moreira to win ONEFC's inaugural lightweight championship.

Aoki presents the toughest fight of his career but Boku believes that if he can steer clear of the Brazilian jiujitsu black belt's array of chokes, locks and strangles he will keep hold of the title.

"We all know what Aoki will try to do. He is one of the best submission artists in the world and will try his best to take the fight to the ground," said Boku, whose black bushy beard threatens to swallow his features and has earned him the nickname 'No Face'.

"I'm confident that if the fight stays standing, I'll be able to knock him out. He might want to bring the fight down but it will not be as easy as he thinks. I've been training extensively on my takedown defence, and if he takes me down, I'm going to get right back up."

KOREAN ROOTS

Boku was born in Japan but is fiercely proud of his Korean heritage and has a tattoo of an ancient Korean 'turtle battleship' over his heart. He studied at a North Korean school in Japan and has both Japanese and South Korean passports.

For many in Korea, wounds are still raw from Japan's brutal rule of the peninsula from 1910 to 1945. North and South Korea are also still technically at war after their three-year conflict ended in 1953 with a truce, not a treaty.

Boku has seen three different sides of the relationship.

"The turtle ship is a homage to my Korean roots. I don't feel ashamed of my Korean heritage," said Boku. "I went to a North Korean school in Japan. The reason is I wanted to learn Korean and they taught Korean in the North Korean schools and not the South Korean schools.

"Yes, they taught (North Korea's) Juche ideology. But we never paid attention to the lessons. Even the teachers brushed off the ideology teachings.

"I am proud to be Japanese. I am also proud to be South Korean. I was brought up with South Korean influences at home, but I also learned Japanese culture through school and friends. I wouldn't definitively say I'm Korean or I'm Japanese."

At 35, Boku sees himself fighting for five more years, though what life has in store for him after that is anyone's guess.

"I always decided I would retire at 40. I don't know what else I will do when I retire though," he said. "I don't know how to do anything else other than fight."

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