South Korea's Yang Ji-ho delivered a career-best nine-under-par 63 in the first round of the Casio World Open in Kochi on Thursday, sharing the lead with Tsubasa Ukita.
The 34-year-old Yang showcased a flawless performance at Kochi Kuroshio Country Club, carding nine birdies to secure his spot at the top of the leaderboard alongside Ukita.
Takanori Konishi follows closely, finishing in lone third with 65.
Yang's compatriots, Song Young-han and Ryu Hyun-woo find themselves in a seven-way tie for fourth, just a shot behind.
This group includes Takumi Kanaya and Taiga Semikawa, who currently hold the second and third positions on the JGTO Money Rankings.
Yang's remarkable performance on the opening day marked his best since his victory at the Hana Bank Invitational, an inaugural event jointly sanctioned by JGTO and KPGA, back in June.
On that occasion, he secured a two-year exemption status on JGTO after defeating Keita Nakajima by one shot at Chiba Isumi Golf Club in Chiba.
Despite making eight appearances since then, with five cuts made, Yang failed to make a significant impact.
However, he expressed satisfaction with his efforts, emphasising that he has been striving to acclimate himself to Japan's playing conditions since choosing to play more regularly with full status here.
"In the latter half of this year, I played on the Japan Tour. The practice environment is superior to that in Korea, and I believe that having more opportunities for practice, especially in short games, contributes significantly to my overall game development," said Yang, whose previous best 18-hole score was a 65.
Despite positioning himself for a potential second win of the season, Yang remains grounded and realistic. He acknowledges that he is still in the process of adjusting to the Japanese golf scene.
"I'm still in the process of acclimating to Japan. While winning would undoubtedly bring joy, my primary focus is on executing what needs to be done and progressing steadily. It's only the first day, after all," said Yang.
Yang had ventured into the Japanese golf scene back in 2012, aiming to broaden his horizons.
He immediately made an impact by winning the Novil Cup on the ABEMA Tour. However, despite playing two full seasons in 2012 and 2013, he couldn't secure further breakthroughs on the JGTO.
However, he was unable to achieve a further breakthrough on the JGTO despite having played two full seasons in 2012 and 2013.
Tour rookie Ukita was just as impressive, making nine birdies to claim a share of the lead for the third time this season.
Of the earlier two strong starts, Ukita translated one into a commendable tied-third finish at the Kansai Open.
Ukita doesn't need to look far for inspiration; he's eager to follow in the footsteps of his former high school mate Yuta Sugiura, who sensationally won the Dunlop Phoenix Tournament as an amateur last week.
"Witnessing a fellow classmate triumph as an amateur ignites a competitive spirit. It's especially motivating when a classmate succeeds," he said.
Currently ranked No. 61 on the money list, Ukita stated that he's entering this week's competition with goals beyond retaining his Tour card by staying in the top-65.
"I'm going to give it my all for the next three days to secure my playing privileges. If possible, I also hope to make the (top-30) cut for the (season-ending Golf Nippon Series) JT Cup (next week)."
Leading first round scores:
63: Yang Ji-ho (Kor), Tsubasa Ukita;
65: Takanori Konishi;
66: Kazuya Koura, Takumi Kanaya, Tomoyasu Sugiyama, Taiga Semikawa, Song Young-han (Kor), Ryu Hyun-woo (Kor), Todd Baek (US).