Curtis had four birdies and only one bogey at the Taiheiyo Club's Gotemba course for a 36-hole total of 10-under 134.
'My shots were not as good as yesterday but they didn't really effect my score,' said Curtis, who had a 65 on Thursday. 'On the par 5s, I was not able to make ideal shots.'
Japan's Toshimitsu Izawa, currently second on the Japanese tour money rankings list, was two strokes back along with Azuma Yano.
Curtis and Australian Robert Allenby are the tournament's two overseas invitees and both were among the 62 players who made the cut at 4-over 148.
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