Hiroshima Carp at Yomiuri Giants - Tokyo Dome - 18:00
Colby Lewis vs. Seth Greisinger
Yokohama Bay Stars at Chunichi Dragons - Nagoya Dome - 18:00
Daisuke Miura vs. Kazuki Yoshimi
Yakult Swallows at Hanshin Tigers - Kyocera Dome Osaka - 18:00
Masanori Ishikawa vs. Yuya Ando
Rakuten Eagles at Nippon Ham Fighters - Sapporo Dome - 18:00
Hisashi Iwakuma vs. Yu Darvish
Seibu Lions at Chiba Lotte Marines - Chiba Marine Stadium - 18:30
Hideaki Wakui vs. Naoyuki Shimizu
Orix Buffaloes at Softbank Hawks - Yahoo Dome - 18:00
Satoshi Komtasu vs. Tsuyoshi Wada
The starters I've listed have been mentioned in various articles as opening day starters so it's entirely possible that someone else is starting.
Incidentally, this is the first time in 6 years that both leagues have started on the same day.