Yoshinobu Tsukada fired a 5-under 67 to move into a two-way tie for the lead with China's Wu Ashun after the first round of the Sun Chlorella Classic on Thursday.
The 42-year-old Tsukada, who is winless on the Japan Tour, took advantage of a hot putter, draining six birdies with a lone bogey on the 7,471-yard, par-72 course at Otaru Country Club. Wu made five birdies in a bogey-free round.
Taigen Tsumagari was one stroke back in a share of third with Kiradech Aphibarnrat of Thailand.
Yoshinori Fujimoto, who had the top finish among Japanese golfers when he placed 54th at the British Open last week, carded a 72 to sit in 45th place. Defending champion Yuta Ikeda got off to a slow start in a round of 75 and was in 98th place.
Sunday's winner will pocket ¥30 million in prize money from the ¥150 million purse.