Kazuhito Tadano (HAM) was tossed after he threw a pitch up and in at Ken Kato (YOM) in the 4th inning. Kato fell backward as his helmet flew off. He was given first base and Tadano was tossed for throwing a dangerous pitch.
Nippon Ham Fighters' manager Hideki Kuriyama rushed onto the field in attempt to get the call reversed, but failed. He gave up the argument because he did not want to be tossed for a delay of game (one of the umpires came over to him to let him know he was getting close to the time limit).
Home plate umpire Koichi Yanada later told reporters that he judged the ball as hitting Kato's helmet. Source: Sanspo 11/1/2012
Fans at Sapporo Dome booed Kato during his next at bat in the 5th inning. It did little to rattle him as he hit a two-run double to left.
Not sure how long they will be up, but there are a few vids over at YouTube.
Someone also posted some videos of fan reactions at 2-chan and NicoDo.
And videos of the fans booing Kato
UPDATE 11/2 @ 8:14am - Some updates...
Kato on the play: "I was so absorbed in the moment, I had no idea what was going on. I saw [the ball] come near my face... I was hit in the head once before. I felt like I did not know what was going on." Source: Sanspo 11/2/2012
FYI: Kato took an HBP off his head on September 4, 2009. Source: Sponichi 11/2/2012
When the umpire explained why he made the call as he did, Kuriyama was not satisfied with the answer and continued to ask "What exactly did you see?" When reporters later ask what the umpire said, he replied, "I cannot say. Just that his opinion and the opinion of the people in our dugout was different, so I asked him what he saw. If he had just said he saw the ball hit him, then I would have walked away. But he said something else so..."
Kuriyama also apologized for the disruption, but not necessarily for arguing a call he was not satisfied with.
Source: Sanspo 11/2/2012
Sports Hochi has some slightly different quotes.
Kuriyama: "His bat was out, so even if it hit him in the head, it should be a strike. Eject me if you like!"
Yanada: "It hit his helmet. This is not something for instant replay. It was a difficult call and I made it in that exactly moment. I do not think it was over the plate."
Source: Sports Hochi 11/2/2012
Catcher Shinya Tsuruoka on what he saw/heard: "It did not sound like the ball hit a helmet. ... It sounded like it hit the bat. I am not sure what to say."
He continued, "Yanada-san first said it was a foul, but that changed after [Tatsunori] Hara came [out of the dugout]. I can not really comment on the ruling."
Source: Daily Sports 11/2/2012