Kenta Maeda was scratched from his start against the Yomiuri Giants today because of tightness in his right arm. According to the Carp, he has inflammation in his triceps brachii muscle.
Maeda complained of tightness in his right arm while playing catch and said, "I was feeling tightness over the last two to three days. I was concerned about forcing myself to throw. It is in a place I have never had problems with."
He is scheduled to sit down with the team trainer to discuss what steps to take next. He will be removed from the active roster if he ends up needing more than ten days for a full recovery.
Shota Nakazaki has been announced as the replacement starter.
UPDATE @ 1:28pm - Additional Maeda quote from Nikkan Sports:
I felt some tightness yesterday and thought I would decide what to do based on how I felt today. I think [not pitching] here is a step I need to take in order to get back as soon as possible.
I do not think this is major. I do not know the cause. I do not think this has anything to do with the WBC.
Source: Nikkan Sports 4/20/2013