Nikkan Sports is reporting that Tae-Kyun Kim could miss the rest of the season with what appears to be a fairly severe back problem. An unnamed club rep said, "His back is apparently in pretty bad shape. He might get better with treatment, but a return this year might not be possible."
The article also mentions that Hayden Penn might be 2-3 days away from picking up a baseball and that he's currently scheduled to return to Japan in mid-July.
UPDATE @ 3:52pm - The Marines hold an option on Kim for the 2012 season (2 year deal + a club option for a third). An unnamed club rep told reporters that since he was a foreign player, he had to show he could put up results before they exercised the option. So it would seem Kim's option year could be in jeopardy depending on whether or not he's able to make it back this season.
Sponichi also has a slightly longer quote regarding Kim's current condition:
His back is apparently in pretty bad shape. He might get better with treatment, but it'll probably takes 2 months after that until he's ready to return. He might not able to make it back this season.
Kim is schedule to get his back examined and a lot will depend on what the doctors tell him.