Junto Nakatani did not need anyone to tell him that Naoya “Monster” Inoue was sitting ringside for his WBC and IBF bantamweight unification bout against Ryosuke Nishida.

“I saw him while I was looking up at the big screens,” he said with a chuckle.

Nakatani (31-0, 24 KOs) put on a show for Japan’s most famous fighter, winning an electric and hard-hitting bout to retain his WBC title, relieve Nishida of the IBF belt and remain on a collision course with Inoue.

Boxing fans around the world are salivating at the prospect of a blockbuster showdown between Nakatani, an undefeated three-weight champion, and also unbeaten Inoue. That fight, which both boxers have agreed to stage, could come in the spring of 2026.

Nakatani had to get past Nishida first.

The bout got off to a start worthy of Natakani’s “Big Bang” nickname, as the pair fought at a frantic pace from the sound of the opening bell, as if each had the same strategy to land big blows early and often.

“Being aggressive in the first round and damaging my opponent was my strategy,” Nakatani said. “I think it was successful.”

The crowd, sensing early on that it might be watching something special, roared in approval through the first few action-packed rounds as Nakatani attacked with vicious, looping left-handed punches and uppercuts as Nishida tried to poke through his defenses.

Nakatani managed to land a couple of blows early on that caused Nishida’s eye to swell.

Nishida's eye kept getting worse as Nakatani pushed forward. He was was exclaimed by the ringside doctor in the fifth round.

The fight was stopped after the sixth due to Nishida suffering a dislocated right shoulder. The 28-year-old suffered his first pro defeat and fell to 10-1.

“It was my first time in a unification match," Nakatani said. "So my focus and my motivation were even higher than in practice."

Earlier, kickboxer-turned-boxer Tenshin Nasukawa maintained his perfect record with a victory over Victor Santillan.

This was a tough fight,” Nasukawa said. “He was a really tough opponent.”

Nasukawa won via unanimous decision, with the judges scoring the fight, 100-90, 99-91 and 99-91. He sounded less-than-pleased after the bout as he stood in the ring drenched in sweat and with blood visible over his left eye.

“I was not able to do well in the match,” he said. The good thing is that we have a lot of work to do.”

Nasukawa, who many fans outside Japan saw for the first time in 2022, when he faced former boxing great Floyd Mayweather Jr. in a high-profile exhibition on New Year’s Eve, improved to 7-0 as a pro boxer.

He ditched his famous platinum blonde look and fought with jet black hair, with the character for “Ten” shaved into the right side of his head.

He walked out to Eikichi Yazawa’s “Tomarabai Ha-Ha,” and his green and black robe glittered under the spotlight once he reached the ring.

Nasukawa landed a couple of solid blows in the fourth round, but Santillan did not look to be in immediate danger. Nasukawa, though, rocked his opponent with three lefts to the head in the ninth inning, breathing life into the partisan crowd.

The fighters aggressively chased the win in the 10th and final round, which devolved into desperate, wild swings from both before the bell rang and Nasukawa wrapped his arms around Santillan.

In other fights, Tomoya Tsuboi survived a 10-round battle against Vietnamese fighter Van Thao Tran to win the vacant WBO Asia Pacific bantamweight title.

Tsuboi could not have asked for a better start to his career, as he claimed a title just 88 days after making his pro debut with a win over Boonrueang Phayom.

Tsuboi defeated Tran via unanimous decision, displaying his speed and hitting his opponent with flurries of punches at points during the fight.

“I felt that Tran was very strong physically and mentally, and it was not going to be easy to knock him down,” Tsuboi said. “So I knew it might go 10 rounds.”

The Osaka native later said he wanted to work on finishing off his opponents in future fights.

“I think I learned a lot today by fighting through 10 rounds,” he said.

Riku Masuda lived up to his growing stature as the successor of the nickname “God’s Left” in the first main bout of the undercard when he floored Michell Banquez in the opening round of their bantamweight bout.

Former bantamweight champion Shinsuke Yamanaka was known as “God’s Left” because of his prodigious power, and Masuda is looking to inherit the mantle from the retired great.

He looked worthy of the name after following a pair of right-handed jabs with a left to the head that sent Banquez straight to the canvas.

Masuda, who has championship aspirations, is ranked No. 7 in the IBF rankings, No. 8 by the WBO and No. 11 by the WBC.

“I think I proved I am a championship-caliber fighter tonight,” he said.