Kazuto Ioka picked the final year of the decade to restore a time-honored tradition.

The four-division and reigning junior bantamweight titlist picked up his first successful defense, turning away the spirited challenge of Puerto Rico's Jeyvier Cintron in scoring a unanimous decision win. 

Scores were 116-112 twice and 115-113 in favor of Ioka in their New Year's Even headliner Tuesday evening at the famed Ota-City General Gymnasium in Tokyo, Japan. 

Cintron showed no fear in fighting on the road and in his first career title fight, outboxing Ioka in what was a tactical affair in the early rounds. The rangy southpaw—whom represented Puerto Rico in the 2012 London and 2016 Rio Olympics—was in his opponent's home region, but held advantages in height, reach and youth, all of which well were served as he used lateral movement and a sharp jab to keep Ioka outside of effective punching range. 

Ever the wily veteran, Ioka found a way to close the gap in round three. Having spent 2/3 of his career on the title stage, the locally-based 30-year old—originally from Osaka, where most of his career has taken place—put his vast experience to good use, working Cintron's body while fending off a late in-round rally from his feisty challenger to take the frame although with a bloodied lip for his efforts.

Cintron refused to back down quietly, enjoying arguably his best round of the fight in the fourth. Coming in with a deceptively-modest knockout-to-win mark of 45%, the unbeaten challenger—who turns 25 in February—planted his feet and scored in combination, also catching Ioka with uppercuts from long range. 

The early deficit was of little concern to Ioka, even a year after coming up just short versus Donnie Nietes in his first attempt at becoming a four-division titlist. Ioka turned the tide in a big way in round five and really never looked back. Cintron continued to box, but a late surge from the defending champ swung momentum in his favor. 

Ioka piled up rounds from there, effectively mixing in-fighting and lateral movement to offset Cintron's attempt to box from long range. Cintron worked every inch of the ring in hopes of tiring the older Ioka, but to no avail as there was less commitment in his power punches. 

The theme carried through for much of the second half of the fight, although Cintron ultimately came alive in the championship rounds. By that point, Ioka had seemingly banked enough rounds to extend his fourth divisional title reign, a body punching display in round 10 seemingly sealed the win barring a dramatic late rounds knockout or at least several knockdowns.

Neither scenario would come close to playing out, though not for a lack of effort. Cintron boxed well throughout the 11th round as Ioka' fought through a rapidly swelling left eye. Hopes of exploding out the gate to start the 12tn and final round were stalled when time was called to repair loose tape on both gloves. 

Cintron went to work from there, boxing well in the final three minutes, but only coming up with a 10-9 round where he really needed so much more in order to claim his first world title. 

Instead, Cintron heads home with his first career defeat in falling to 11-1 (5KOs). His first fight on this stage and in Japan came following a pair of bouts with Japan's Koki Eto, both taking place at Osceola Heritage Park in Kissimmee, Florida.

The first fight was brief yet long enough to spark a major controversy, if only for a few minutes. Eto was deemed to have won by 1st round knockout in their late May clash, only for replays to show a headbutt as the deciding blow in changing the verdict to a No-Decision. 

Their rematch came just 10 weeks later, with Cintron enjoying a much better night at the office in the very same venue. An early knockdown paved the way for a decisive points win and with it, the right to challenge for the 115-pound title. 

His valiant effort on Tuesday wasn't enough to produce the same kind of magic, as Ioka (25-2, 14KOs) closes out the decade as a defending champion while restoring a time-honored tradition he helped kick off eight years ago. 

The first New Year's Eve headliner came during Ioka's strawweight title reign in 2011, picking up his third knockout win in as many title fights to close out a Fighter-of-the-Year level campaign. It was the first of six consecutive year-ending title fight wins for Ioka, with the tradition broken in 2017 upon abruptly announcing his retirement one month prior and with it, abandoning his flyweight title reign.

As is the case with most boxing retirements, Ioka—upon the advice of manager Taku Nagashima—gave it another run as he returned to the ring last September, which also marked his first career fight in the United States. A win over Puerto Rico's McWilliams Arroyo helped position him for a shot at becoming Japan's first-ever male boxer to claim titles in four weight divisions. 

Ioka would need two tries in order to join Naoka Fujioka on that stage, as he came up just short in a New Year's Eve 115-pound title clash versus Philippines' Donnie Nietes, who himself became a four-division titlist with the win in Macao. 

Six months later came the type of history Ioka sought, knocking out Philippines' Aston Palicte in 10 rounds to win the title he successfully defended on Tuesday. With the victory, Ioka closes out the decade with a 16-2 record in major title fights. He also ends the 2010s with a 7-1 mark in New Year's Eve headliners, with the latest victory only adding to his Hall of Fame credentials. 

The bout aired live on TBS-Japan. 

Jake Donovan is a senior writer for BoxingScene.com. Twitter: @JakeNDaBox