Nagano fired six birdies and no bogeys at Chiba Country Club, southeast of Tokyo, and was followed by Jason Knutzon of the United States, who shot a five-under 66 with five birdies.
The Japanese golfer’s thoughts were with the citizens of his hometown of Kumamoto, which was hard hit by two powerful and deadly quakes that rocked the southwestern island of Kyushu last week and that have forced tens of thousands of people to flee their homes.
“I hope I can be of help,” Nagano said ahead of the tournament.
“I want to do my best.”
Organisers cancelled a series of pre-match events in an effort to trim costs and send 10 million yen ($91,000) in donations for the disaster area.
Six players — Park Sang-Hyun, Hidemasa Hoshino, Chapchai Nirat, Wu Ashun, Azuma Yano and Yuta Ikeda — shared third place after shooting four-under 67s.
66 – Jason Knutzon,
67 – Park Sang-Hyun, Hidemasa Hoshino, Chapchai Nirat, Wu Ashun, Azuma Yano, Yuta Ikeda
68 – Panuphol Pittayarat, Shiv Kapur, Kazuhiro Yamashita, Akio Sadakata