It was only a matter of time, really.
A nation like Japan, a world leader, booming economy, and now in need of military strength for serious defense in a volitile part of the world, needs a strong military. Their economy isn't doing as great as it was once doing and the PM can't get respect from the people. A military would certainly boost the economy, even if it at first triggered debt.
I'm not saying the strategy to pull pacifism is motivated solely by economics, but cash talks. The Japanese people are a very honor-driven people with fierce loyalty. Stories of their amazing resolve in WWII astound me. Their bravery is almost unparalleled. Yet the Japan of today is not what it was in WWII. There is no Emperor whom one should be unquestionably loyal LIKE there was in WWII. And he is not a god in the people's eyes. The Japanese are very modern. They are well-educated and have a lot on the line concerning giving up pacifism. The PM desires to honor his country and his people; with indiviualism a heresy in Japan, the people will speak with a more or less solid voice regarding their wishes.
Right now, I think they are wary of leaving the "security" pacifism seems to offer. However, growing sentiment says they will do what is right and they strongly desire to protect themselves from their increasingly agressive neighbors.
As N Korea and China become more agressive toward Japan, I look for a drastic swing in public sentiment toward military support. As I've already written, we could be looking at the events leading up to a WWIII as nations become increasingly fearful of unstable nearby regions. Japan is a nation to watch closely right now. They may be the very ones who throw the gauntlet.