Rookie southpaw Kazuma Sato threw five scoreless innings on Sunday and earned the win as the defending Pacific League champion Orix Buffaloes completed a three-game interleague sweep of the Yomiuri Giants with a 4-1 victory. Sato (1-0) allowed two walks and a hit while striking out three at Tokyo Dome. He took to the mound in the bottom of the first after Orix seized a 2-0 lead against veteran Tomoyuki Sugano (5-1). “I’ve been nervous for the last two days since learning I would start,” said the 23-year-old Sato, who joined Orix on a developmental contract in 2019 but had spent his whole pro c…