Matsumura, who just happens to be the defending champion in the event, recorded an opening round of 60 over the par 70 layout, one good enough to be been used for a previous Japan Open, but today the magic was not quite the same.
Two early birdies were soon overtaken by a series of bogeys but the 30 year old who also won the Indonesian PGA Championship earlier this year in the opening event of the Japan Tour schedule finished with a round of 70 and shares the 36 hole lead with Korean Hyung Sung Kim.
Former winner Ryo Ishikawa is threatening danger in a share of 5th position, three shots from the lead.
The leading Australasian is Steve Conran, a runner-up in this event in previous years who shares 7th position.
Brad Kennedy followed his opening 65 with a round of 73 to be in a share of 18th, Michael Hendry is 1st, David Smail 30th and Kurt Barnes despite a round of 76 looks like he will just make the cut.