To be fair, Japan tried pacifism for a long time:
Prime Minister Shinzo Abe, buoyed by a huge election win for lawmakers who favor revising Japan's post-war, pacifist constitution, signaled a push towards his long-held goal on Monday but will need to convince a divided public to succeed.
But pacifism didn't prevent prevent China and North Korea from threatening Japan.
So Japan may try the traditional method of defending itself--a military like every other major power has.
China might find itself in more dangerous waters if Japan does that and then spends even 2% of their GDP on defense.
I assume this is part of the pressure on China to do something about North Korea before bad things start happening in response to North Korea's march to a nuclear arsenal.
I bet Abe would rather not have this fight and would pull back if China solves the North Korea nuclear problem once and for all.
So congratulations to Peking on their foreign policy that is pushing Japan to become a "normal" country with a military.