The military buildup has been a rising trend since the Koizumi administration. However, going as far as acquiring nuclear weapons is very unlikely. A nuclear option will not only meet stiff resistance in the Japanese Diet, but also under the general populace.
I did a paper not a long time ago on the subject of the international anti-nuclear movement. Japan was and still is, without a doubt, the most
anti-nuclear country in the world. The memories of the atomic bombings of Hiroshima and Nagasaki are still fresh and this is an event that both the politicians in the Diet and the ordinary Japanese will never forget, EVER. It has come to the point where even civilian nuclear technology has become such a controversial topic in Japan, that you won't be able to even get to the possibility of acquiring military nuclear technology, even if Shinzo Abe wanted to.
For those who are interested, you should read
A history of the World Nuclear Disarmament Movement series by the historian Lawrence S. Wittner. He has done an excellent job in researching this subject, with the anti-nuclear movement in Japan through the 1950s-2000s included.
So yes, the Japanese are certaintly pushing for a conventional military buildup with maybe even some ABM capabilities, but nuclear weapons? In the foreseeable future? No.
Tell me,
@Nihonjin1051, what's the opinion of the average Japanese regarding CIVILIAN nuclear technology?