Hidemasa Hoshino opened up a two-stroke lead at the Mynavi ABC Championship after the 32-year-old posted a second-round 69 to move to nine-under.
Hoshino carded five birdies against two bogeys at ABC Golf Club to break clear of a chasing pack that features Toro Suzuki, Hiroyuki Fujita and teenage star Ryo Ishikawa.
Suzuki signed for an eventful five-under 67 that featured an eagle, six birdies and three bogeys, while Fujita shot a 68 and Ishikawa a 69 as they trio finished seven under.
Shintaro Kai lies fifth on six under following a 69 and Korean Kim Hyung-sim is sixth after recording a disappointing one-over-par 73.