By Jake Donovan

Kosei Tanaka continues to prove well advanced beyond his 20 years of age, surviving a tough challenge from Vic Saludar to score a 6th round stoppage win Thursday evening in Nagoya, Japan. 

The defending strawweight titlist was down in round five and under siege in round six before a left hook to the body put Saludar down and out to end the fight at 2:15 of round six.

Tanaka made history for his native Japan in topping Julian Yedras over 12 rounds this past May to win a vacant strawweight title. The feat came in just his 5th pro fight and at two weeks shy of turning 20, surpassing both marks previously set by Naoya Inoue, who just 13 months prior won a junior flyweight belt in his 6th pro fight and four days before his 20th birthday. 

Whereas his ambition matches that of Inoue and Kazuto Ioka - who claimed his first title in his 7th pro fight - Tanaka has yet to fully develop his skill set or mental discipline. It showed in his 12-round war with Yedras and again on Thursday with Saludar, who showed no fear in both his first title fight as well as his debut outside of his native Philippines. 

The fight was a free-swinging affair from the opening bell, which ultimately played to Tanaka's benefit. It didn't always appear that way, as Saludar at times couldn't miss with his right hand. That very weapon produced the first knockdown of the fight, clipping Tanaka upstairs to drop the defending champion in round five.

Saludar remained on the attack for the rest of the round and well into round six, unaware that he was actually playing right into the champion's hands. The local favorite turned the tide at a moment's notice, drilling the visiting challenger with a left hook to the rib cage. Saludar doubled over in pain, avoiding an ensuing right hand only as he collapsed to the canvas as referee Michael Ortega ultimately stopped the contest. 

The knockout loss snaps a nine-fight win streak for Saludar, who heads back to Philippines with his record now at 11-2 (9KOs). 

As for Tanaka, his record advances to 6-0 (3KOs), though there exists the concern of whether or not he's showing improvement just two years into his pro career. It's clear that he loves a good brawl, which will always leave him in good graces with TV network brass. How far the good times can last remains to be seen.

At 5'4½" and still growing as a 20-year old, his time spent in the strawweight division could be brief. There has been talk of moving up to junior flyweight as early as his next fight. The intention would be to chase a major title at the weight - the goal being to break another of Inoue's record in becoming the youngest and the quickest to title wins in two weight divisions. 

For now, he can rest easy on ending 2015 with a bang.

The bout aired live on MBS-TV, kicking off one of three New Year's Eve boxing telecasts from Japan.

Jake Donovan is the managing editor of Twitter: @JakeNDaBox