Yanagita hit a two-run triple off Iwakuma in the second for a 3-0 lead, singled in the go-ahead run in the fourth, walked against Rob Wooten in the sixth and had an RBI double off Tsuyoshi Wada in the eighth.
"Yanagita has a lot of bat speed," MLB manager John Farrell said. "He's aggressive, and whether it is against a left-handed pitcher or a right-handed pitcher, he has swung the bat very well."
Hikaru Itoh hit an RBI single in the three-run second. NL batting champion Justin Morneau hit a two-run homer off Chihiro Kaneko in the bottom half, and the major leaguers tied it in the third when Ben Zobrist tripled and scored on Jose Altuve's grounder.
Nobuhiro Matsuda led off the eighth with a homer off Wada, a former teammate, that made it 7-3. Zobrist doubled in the bottom half and scored on Robinson Cano's single.
Iwakuma allowed five runs and 10 hits in four innings.
Kaneko, the winner, gave up three runs and three hits in five innings, struck out five and walked two. Tomomi Takahashi retired the side in the ninth, completing a six-hitter.
"You want to represent MLB well," Morneau said. "Whether we're playing basketball or checkers against my wife. In the end it comes down to wanting to win. We're here to win the series. We know what we are up against, so we'll try to come out tomorrow and hit the ball well, so we can win the next game and go from there."
NOTES: Kansas City RHP Jeremy Guthrie will start Game 3 on Saturday, while Rakuten Eagles RHP Takahiro Norimoto will take the mound for Japan.