Kenshiro Teraji produced a stunning, come-from-behind 12th-round TKO win over Seigo Yuri Akui to unify the WBC and WBA flyweight titles in one of the fights of the year at the Ryogoku Kokugikan in Tokyo.

Akui, who looked to have been ahead on the scorecards heading into the final round, landed hard right and left hands all night. All he needed to do, it seemed, was win the final round.

It was confirmed that the scores read 105-104, 105-104 to Akui and 106-103 to Teraji at the time of the stoppage, meaning that Teraji needed at least a knockdown to swing the fight in the final round.

But 29-year-old Akui was left devastated and in tears at the end of their world title clash, after being stopped following one final flurry from his opponent, who came out for the 12th round like a man possessed.

"Yuri was a very tough opponent, I want to fight at super-flyweight next. I barely got this victory, this fight was heart vs heart. I'm victorious because I had all the team and support behind me," Teraji said in the aftermath.

For just the third time ever, two Japanese champions would look to unify world titles and the atmosphere said it all as both men walked to the ring; Akui (21-3-1, 11 KOs) dressed to the nines in a neon-coloured number, while Teraji (25-1, 16 KOs) strolled in to the reverberating echoes of heavy metal guitar riffs.

WBC 112-pound champion Teraji had been in this position before, previously unifying against Hiroto Kyoguchi for The Ring, WBC and WBA flyweight titles in November 2022.

But WBA flyweight champ Akui was here to represent what he hoped would be an even more arduous task. And it showed in the first round; Akui refusing to take a step back, landing stiff jabs and right hands while Teraji looked to counter.

Though he was a favourite coming into the night, Teraji found himself on the back foot yet again in the second. More jabs and right hands from Akui followed, but it was Teraji who unleashed a beautiful combination on the inside with under a minute to go.

Akui, who in the build-up spoke of his aim to put his home city of Kurashiki on the map, fought with even more purpose in the third, rocking and socking his opponent with big right hands and left hooks. The biggest shot of the round came when both men looked to trade jabs. As the pair reset to throw a right each, it was Akui who landed his first.

Teraji, The Ring's No. 2 flyweight, targeted the body in the fourth round, but Akui replied with a big right hand over the top. Both men, it was clear, fancied a firefight as the middle rounds approached. Akui, yet again, was the man to finish the round strong, landing a big right hand before sending a combination down to his opponent's body.

The Ring's No. 3 flyweight Akui came back out for the fifth with more front-foot pressure. Teraji responded in kind with an uppercut-right hand combination before Akui came back with a massive right hand moments later.

In the last 30 seconds of the fifth, Akui's physicality showed as he landed numerous jabs and right hands, backing his man into the ropes in the process.

The sixth round saw the fight's most exciting action. Both men would not yield, coming forward to throw right hands, left hooks and uppercuts on the inside. Teraji had decided that backing up was not the way to win this fight, it was to fight fire with fire. And Akui was more than happy to oblige. By the end of the round, Akui had gained control once again, dishing out punishment to both the body and head.

Teraji came out for the seventh with a serious purpose. The game plan was to throw and throw often, with both men setting a ridiculous pace in a round that the most eagle-eyed judge would find difficult to separate. Akui stood up to most of what came his way, and he threw back just as much as he received, but there was a definite shift in momentum.

The eighth round saw Teraji return to his jab. Earlier in the fight the slower pace hadn't worked but now that Akui was zapped of a little energy, the favourite took his opportunity to try and get rounds in the bank.

Akui was privy to Teraji's plan, though. He continued to push through the fatigue, landing two big right hands which shook Teraji back onto the ropes.

After a tiring eighth, Akui approached the ninth with a similar energy to what he showed in the early rounds. Stalking his opponent, marching forward, looking for openings, it was the underdog, once again, who scored the biggest shots; the most eye-catching a huge right hand as Teraji pulled away from an exchange in the middle of the ring. Akui finished the round stronger too, landing an accurate one-two seconds before the bell sounded.

By the 10th and 11th round, the fight was in Akui's hands. Every time it looked like the momentum might shift the way of Teraji, Akui would land something back to break the spirit of his more experienced opponent.

And with 30 seconds left in the penultimate round, a big left hook around Teraji's guard rocked the Kyoto fighter on to his heels, which Akui followed up with a devastating combination to the body.

Then came the drama. The final round saw Teraji put forward an entirely different energy. He was going for the knockout. His pace was relentless and all of a sudden an exhausted Akui had resorted to hanging on and attempting to coast until the end of the fight.

After a vicious combination up against the ropes, Akui moved to the centre of the ring but Teraji followed and landed an earth-shattering right hand which stumbled Akui badly. The referee had seen enough. In he stepped to halt the contest, ending Akui's dreams in the process.

Akui had put up the fight of his life until that point, doing much more than many expected, leaving Teraji needing something spectacular to come away with two belts in hand. Teraji stood up to all of Akui's punishment and then some. And though he could barely believe it, it was he who was left standing tall with two belts at the end of an absorbing night in Tokyo.