I was just watching the news when they announced that Shigeru Kobayashi passed away today. There wasn't any more information provided other than that so I searched around and found an update at Yomiuri Online.
According to the article, it was a sudden and unexpected death. The reason listed is heart attack. He was only 57.
Kobayashi was set to become the Nippon Ham Fighters pitching coach this season.
=== UPDATE 1/19/2010 3:26pm JST
Seems Kobayashi was abstaining from alcohol last month due to high GTP levels in a recent blood test.
Koji Yokoyama told reporters that Kobayashi told him on December 23rd, during a party thrown for Orix Buffaloes' 3rd round draft pick Nobuyoshi Yamada, that his GTP levels were high so he was holding off from drinking alcohol. Kobayashi also apparently told Yokoyama that his dream was to manage the Fukui Miracle Elephants out of the BC League. That would then allow him time to continue coaching elementary school kids in the evening.
The Fighters are also currently mulling over the idea of holding a memorial game for Kobayashi. The Fighters could select an exhibition game they'll be playing against the Hanshin Tigers on 3/3 at the Sapporo Dome for this.
=== UPDATE 1/20/2010 1:11am JST
About 300 people attended Shigeru Kobayashi's wake on Tuesday.
=== UPDATE 1/20/2010 1:41pm JST
Funeral services are being held today.
Kobayashi will be getting a special corner in the Koshien Museum of History.
=== UPDATE 2:31pm JST
Seems the Fighters are now thinking about making one of their practice games against the Tigers (2/13 or 2/14) a memorial game.
The Fighters also won't be handing out the uniform number 79 to anyone anytime soon.
=== UPDATE 4:20pm JST
About 300 fans paid their respects by leaving flowers at the Ni-gun training facilities in Kamagaya on Wednesday.
=== UPDATE 1/21/2010 2:18pm JST
It seems 450 telegrams arrived at Kobayashi's funeral on Wednesday.
=== UPDATE 1/22/2010 8:01am JST
Masataka Nashida paid his respects by visiting Kobayashi's family on Thursday.