Ioka, The Ring's No. 10-rated bantamweight, was Japan's first-ever male four-weight world champion and has achieved so much in the sport.

However, the 37-year-old boxer-puncher is now shooting for immortality, as he bids to become his country's first male five-weight ruler at the expense of WBC 118-pound titleholder Takuma Inoue at the Tokyo Dome on Saturday.

In December, Ioka debuted at bantamweight with a brutal fourth-round body shot knockout of unheralded Venezuelan Maikel Ordosgoitti. Trained by the excellent Ismael Salas, the challenger is fully prepared for Inoue and has done everything asked of him in camp.

"I think I have a better quality of conditioning because I had a fight before [in the bantamweight division] and I'm now coming into my second one," Ioka told The Ring.

"I feel comfortable because I have experience with making this weight now. I didn't really struggle to make 115 pounds, but it was the right time to move up."

Inoue, who is rated No. 3 by The Ring, has struggled in the shadow of his older brother Naoya for several years. It was November's 12-round unanimous decision over the previously-unbeaten Tenshin Nasukawa, a career-best performance, that saw him finally recognized internationally as a terrific professional in his own right.

"I respect him," Ioka stated in earnest. "In terms of boxing skills, he's good at distance. I can't tell you what his weaknesses are, I'm not giving anything away, but there are weaknesses.

"He was great against Tenshin [Nasukawa], but experience played a big part for Takuma. Again, he was great at distance, that's how he overcame Tenshin's speed and technique."

Ioka (32-4-1, 17 KOs) was stoic and taciturn throughout our conversation, but his eyes lit up when reminded that he has the potential to become Japan's first five-weight world champion.

A professional for 17 years, Ioka would join a host of all-time greats if he could pull this off.

The only male fighters in history to win five divisional titles are Sugar Ray Leonard, Thomas Hearns, Oscar De La Hoya (six weights), Floyd Mayweather, Manny Pacquiao (eight weights) and Terence Crawford.

"I'm so happy that I'm able to challenge for this feat," Ioka said. "It's hard to explain the status that I can achieve by becoming a five-weight world champion. It's incredible, so I'm grateful [for this chance].

"I will be the champion once again and will prove myself. I lost two in a row (to Martinez) at junior bantamweight, so getting back to championship status at bantamweight will show everybody how great I am. I will prove my strength in this weight division."

Inoue vs. Ioka will serve as the co-main event before the undisputed junior featherweight championship match between Naoya Inoue and Junto Nakatani. Being one of the most decorated fighters in Japanese boxing history, Ioka's opinion on the outcome of this matchup is more valuable than most.

"It's a difficult question," acknowledged the ex-champ after a very long pause. "Naoya is superior in many ways. I think Naoya is going to win, but we can't expect anything in boxing.

"Junto has a strong will for this fight in particular. Something just might happen."