The 31-year-old had rounds of 65, 67, 67 and 68 to finish 21 under par around Damai Indah Golf's 6,545-metre (7,160-yard) Bumi Serpong Damai course to claim the $180,000 first prize at a tournament co-sanctioned by OneAsia and the Japan Tour.
Australian Rhein Gibson (62) and Filipino Juvic Pagunsan (69) shared second place, while China's Wu Ashun (69) was alone in fourth.
Matsumura trailed overnight leader Park Sang-hyun by a shot going into the final round and looked to have blown his chance after starting with a bogey and then doubling the sixth. But six birdies on a blistering back nine -- none better than on the 17th when he drained a 24-footer -- saw him home.
A three-time winner previously on the Japan Tour, including last year's Crowns event in Nagoya, Matsumura said he was delighted to win abroad for the first time.
"It has been my dream since I became a professional to win a tournament outside Japan," he said. "It is a great honour to win this title at such a beautiful course."
Gibson had set the pace much earlier in day with a scorching 62 that equalled the course record set by Gaganjeet Bhullar in 2007.
The 28-year-old, a graduate of OneAsia Q-School in 2013, is the official world record holder of the lowest ever score by a professional -- a 17-under-par 55 he managed at River Oaks Golf Club in his adopted home of Oklahoma -- but Sunday's round was a career best in a sanctioned tournament.
Gibson, who finished fourth at OneAsia's Emirates Australian Open last year to earn one of three slots available to Britain's 2014 Open Championship, had an eagle, ten birdies and two bogeys in an astonishing round that was interrupted when he was on the 17th for nearly three hours by a sudden thunderstorm.
"I had some good yardages and just hit it to within a couple of feet," he said. "I had some really cheap birdies and that's what really got me going."
Gibson earned US$87,500 for his efforts.
Bogeys on 10 and 14 saw Pagunsan, a winner here in 2007, slip out of contention, but he birdied three of the last four holes to bounce back into contention.
"It just wasn't going to be the day today," he said.
The leading Korean finisher was fifth-placed Maeng Dong-seop (65) who closed at 17 under par, while George Gandranata (71) had a share of 37th at nine.
OneAsia's next event is the 20 million Yuan (around $3.2 million) Volvo China Open at Genzon Golf Club from April 24 - 27.