The absence of a smile from Junto Nakatani’s face was noticeable as he made weight for the first defense of his WBO junior bantamweight title reign.

If nothing else, it was an instant reminder of what he previously had to endure during his time spent as the WBO flyweight titlist.

“I struggled to make 112 pounds and spent a lot of time to make weight,” Nakatani confessed to “When I moved up to 115 pounds, I have felt stronger and I was able to train harder.”

Nakatani (25-0, 19KOs) will defend his WBO junior bantamweight title versus Mexico’s Argi Cortes. The bout will air live on Amazon Prime Video in Japan and ESPN+ (Monday, 5:00 a.m. ET) in the U.S. from Ariake Arena in Tokyo.

The bout is the co-feature to the Kenshiro Teraji-Hekkie Budler lineal/WBC/WBA junior flyweight championship.

The bout will be his third straight at junior bantamweight since he moved up from the 112-pound division. He outpointed Francisco Rodriguez last November 1 but delivered the best performance of his career in a 12th round knockout of Australia’s Andrew Moloney—a former WBA ‘Regular’ junior bantamweight titlist—to win the WBO 115-pound title on May 20 in Las Vegas.

There will come a point where Nakatani will consider the chance to become a three-division titlist and perhaps climb even higher. For now, weighing even just three pound heavier than was the case more than a year ago is good enough.

“I don’t know how many divisions I can move up. Physically, I’m confident I can fight at 122 or even 126 pounds,” said Nakatani. “As It gets harder to make 115 pounds, I will consider moving up another division.

“But not right away. For now, I still want to unify the division.”

Jake Donovan is a senior writer for Twitter: @JakeNDaBox