Michihiro Ogasawara hit another three-run home run as the Giants overcame a sluggish start by Seth Greisinger on Friday to win their third straight.
Yomiuri also got a two-run homer from Lee Seung Yeop and needed it to keep the Chunichi Dragons at bay before blowing them out 10-4 before 42,927 at Tokyo Dome.
"We kept scoring, but it was good to get off to a good start," Ogasawara said of his first-inning homer. "The guys in front of me got on. I was concentrating just as much as usual, but I reacted particularly well."
Greisinger pitched better than actor Tom Hanks, but still needed a lot of help from his teammates to make a game of it.
After Hanks bounced the ceremonial first pitch to the backstop, Greisinger took over. The right-hander walked the first batter he faced and hit the next before getting out of a one-out bases-loaded jam with a double play.
It was the first of four twin-killings Greisinger (4-2) would get in six innings on the mound that saw him surrender four runs on 10 hits, two walks and a hit batsman. The right-hander struck out one.
Moments after Greisinger's first brush with disaster, Dragons starter Daisuke Yamai (0-2) put himself in hot water with back-to-back walks in the bottom of the inning. Ogasawara, whose three-run, eighth-inning shot brought the Giants from behind on Thursday, hammered one deep into the right-field stands for his eighth homer of the year.
The Giants stranded two against Yamai, who only lasted one inning, and two more in the second against Maximo Nelson before Lee made it 5-0 in the third.
Nelson walked Yoshiyuki Kamei to open the inning and Lee, who hit two out on Thursday night, smoked one.
"I'm still getting back in form," said Lee, whose 3-for-5 night boosted his average to .237. "I'm ironing out kinks in my swing one by one. It's not something that is going to happen overnight.
"Now I want to come back and do some good tomorrow."
The Dragons got back those two in the top of the fourth on Tony Blanco's tape-measure solo shot and an RBI double by Keiji Oyama.
Blanco, who hit the ceiling with a two-run homer the night before in Nagoya, blasted a leadoff shot high off the wall above the stands in left-center field for his sixth home run of the year.
Singles by Kazuhiro Wada and Atsushi Fujii set Greisinger up for his third double play of the night, but Ogawa doubled Wada home with two outs.
In the bottom of the inning, Tetsuya Matsumoto scored the Giants' sixth run. The No. 2 hitter reached for the third straight time, went to third on an Ogasawara single and scored on Alex Ramirez's second hit.
The game got off to an awkward start when Hanks, in Japan to promote his latest film, "Angels & Demons," bounced his pitch past director Ron Howard.
"I bounced it in the dirt. I'm humiliated," said Hanks "I went from the rush of being in this sacred spot to humiliation and being mortified. This is the team of Sadaharu Oh, for crying out loud. There is a lot of baseball history out there."