The champion was a solid amateur, running up a 39-16 record and captaining a University team, which saw him mixing with solid amateurs on a regular basis. He turned professional in 2014, fighting to a 6 round draw with Daishi Nagata on debut, and since then has found his grove, settled into the sport and become a really talented hopeful.
In the ring Inoue has shown a bit of everything. He can box, and is pretty solid behind his jab, he can fight on the back foot and he can bring the action with a pressure style, a style that helped him score a brilliant win earlier this year against Akinori Watanabe and really break away from the other domestic contenders. Last time out he again impressed as he stopped the usually tough and highly experienced Koshinmaru Saito.
Although not a puncher Inoue has enough power to keep opponents honest, he has a great engine, a good work rate and can either box or fight. His problem, going forward, is that he might look to fight with the wrong type of opponent, being dragged into wars when he doesn't need to be, he's also not really proven his ability to go 10 rounds or his ability to take a really good shot. We suspect he can, at least at domestic level, but we've not got proof he can.
Ranked #1 by the JBC Nagahama is a fighter getting a huge chance to claim his first title, despite having only been in one bout scheduled for 8 rounds or more. That leaves questions about his stamina, and with only 26 total bouts, including an 11-7 amateur record, to his name he also lacks experience.
Whilst it's easy to pick flaws with Nagahama there is a fair bit of positivity to take from his career so far. He debuted in June 2015 and by the end of the year he had claimed the Rookie of the Year crown at Middleweight. The following year he dropped down in weight and began to find his grove, stopping Tetsuya Kawabata in July 2016 and then Koji Kase in November. That win showed that Nagahama was an aggressive and exciting fighter, who liked to come forward and let his hands go, though he did so with mixed success and often missed the target all together.
For Nagahama the bout is a massive step up in class. He's now up against his first opponent with real proven ability. More worryingly for the challenger is that his style should gel with Inoue's too well, and they could be almost like mirror images in the middle of the ring, with Inoue have almost every advantage. If that's the case then there will only be one winner, Inoue, and that win will likely be by late stoppage from accumulation.