10:57pm: Geoff Baker of The Seattle Times reports (on Twitter) that the incentives kick in at 20 starts, at which point Iwakuma will be paid a $200K bonus. He will make $250K for 22 starts, $300K for 25 starts, and $400K for 30 starts. The innings bonuses kick in at 140 IP, and he can earn another $400K for 200 IP.
Iwakuma spent four days in Seattle back in December according to Baker, during which time he met GM Jack Zduriencik and was shown around town. He didn't speak to Ichiro Suzuki before signing, says Baker (on Twitter).
7:35pm: The Mariners have agreed to sign right-hander Hisashi Iwakuma to a one-year contract worth $1.5MM, reports ESPN's Jerry Crasnick (all Twitter links). The deal includes $3.4MM in incentives based on starts and innings pitched. We heard the two sides were closing in on a deal earlier this week. Iwakuma is a Sosnick-Cobbe client.
The Rakuten Golden Eagles posted the 30-year-old righty a year ago and the A's won the rights to negotiate with him for $19.1MM. However, the sides didn't work out a deal and Iwakuma re-signed with Rakuten. He posted a 2.42 ERA with 6.8 K/9 and 1.4 BB/9 in 119 innings in 2011 and became a true free agent after the season. He figures to join Felix Hernandez, Jason Vargas, and Michael Pineda in Seattle's rotation with Blake Beavan and Charlie Furbush as candidates for the fifth spot.