The Japanese fighter began the fight strongly, scoring a pair of first round knockdowns.

Yet he was unable to finish his title defense early as the Mexican challenger showed heart to stay the course, ultimately dropping a lopsided 12-round decision (118-108, 118-108, 116-110).

"I started the fight well, but from the second round onward I became too tense and tried too hard," Yabuki told The Ring.

"My opponent became very cautious and defensive, and instead of stay composed, I ended up forcing things.

The 33-year-old knockout artist entered the second defense of his 112-pound crown having stopped his last six opponents and admits he was frustrated not to make it seven against Calixto.

"Looking back, it was a fight I could have finished by knockout but let my emotions get the better of me and things didn't go as planned," he accepted.

"Honestly, I felt nothing but frustration. I won the fight, but it felt like I had lost to myself. It was one of those performances where, despite getting the victory, I wasn't satisfied at all with what I showed in the ring."

However, Yabuki (20-4, 18 KOs) has raised a high bar in recent years after suffering early career defeats. A tough love approach was adopted against future world champions Junto Nakatani (UD4, 2016) and Seigo Yuri Akui (TKO1, 2018) and served him well.

He used those experiences and galvanized himself to score a stunning 10th-round stoppage of long-reigning WBC champion Kenshiro Teraji in September 2021, though Teraji avenged defeat six months later (KO3) in an immediate rematch.

To his credit, the Nagoya resident has gone from strength to strength since, taking the notable scalps of future IBF junior flyweight titlist Thanongsak Simsri (TKO7, 2022) and Sivenathi Nonthshinga (TKO9, 2024) to become the sanctioning body's junior flyweight champion.

He then decided to move up to flyweight where he won the IBF strap with a 12th-round stoppage of Angel Ayala, then history repeated itself in his maiden defense against former IBF 108-pound kingpin Felix Alvarado in December.

"I've faced a lot of strong fighters throughout my career," he said.

"Back then, I was still inexperienced and relatively early in my professional journey, so there were fights that I lost. But now, with the experience and confidence I've gained, I don't believe I would lose to any of those opponents if we fought again."

His manager Manabu Murakami has seen Yabuki rise and reach unexpected heights.

"I feel that Masamichi continues to improve with every fight," said Murakami. "Even when I watch him in training, I don't get the sense that he's going to lose to anyone right now.

"As long as he remains a champion and keeps that mindset, I believe he will continue to evolve and become an even better fighter."

Meanwhile, Yabuki hopes to continue to face the best opposition available though wouldn't be drawn on anyone specific.

"Whether it's at flyweight or junior bantamweight, if there's an opportunity to fight a world champion, I'm ready," he said. "I'll fight anyone, anywhere, as long as it's for a meaningful challenge."