Japan’s league champs each won Game 1 of its Climax Series playoffs final stage on Wednesday, the Pacific League’s Orix Buffaloes beating the Lotte Marines 1-0 behind a four-hit shutout from Yoshinobu Yamamoto, and the Central League’s Yakult Swallows downing the Yomiuri Giants 4-0 behind a six-hitter from rookie Yasunobu Okugawa. Each league champ begins the best-of-seven final stage with a one-win advantage and now leads its series 2-0. The team with the most wins advances to the Japan Series, while the league champ will also advance if the series ends in a tie. The 23-year-old Yamamoto, who…