Today the two men took part in their weigh in for the contest and both men made the 140lb limit.
At the weigh in both men made 140lbs dead on. For Aso, who is taking part in his third Japanese title bout, the bout sees him coming in slightly heavier than he has for previous title bouts, but looking in great shape and like a fighter who know this could be his final title opportunity.
For Matsuyama, who is fighting in his first title bout, the weight is the same as he's been in a number of recent bouts, including his 2016 loss to Daishi Nagata and his draw with Kentaro Endo. Although he is winless in almost a year he looked in amazing shape and it's clear he's not looking to make up the numbers here.
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(Image courtesy of boxingnews.jp)