Rising Sun

It's hard to say if this story is more straight-up - based on Japan's need to defend itself against a loony North Kora and a militarizing China - or posturing - based on the need to win concessions eliminating the the North Korean nuclear threat. Given the timing, I'd lean to the first choice, but I suspect there are elements of both at work:

Japan's Prime Minister Junichiro Koizumi said Tuesday his party would unveil ideas later this year on amending the U.S.-imposed constitution amid calls to end the country's official pacifism.
[...]
Such a change would mark the first revision to the pacifist 1947 constitution imposed by the United States at the end of World War II, in which Japan renounced war and the right to maintain a military.

Analysts have warned that constitutional changes could enrage neighboring Asian nations that suffered under Japan's wartime aggression.

A constitutional revision would require a two-thirds majority vote in both houses of parliament and a majority in a public referendum.

I doubt the significance of this announcement will be lost on the Chinese in particular.