The populace is, for now. Expansions of the JDF and general worldwide rise in nationalism with Korea going nuclear, the decline of America and China being aggressive off of the Ryukyu islands can change that quite rapidly. I looked it up and there's general consensus that they can build ICBMs in 6 months with their 9 ton stockpile of plutonium and enriched uranium and using their rockets off the shelf, if they haven't already just secretly built the warheads and stored them.

Seems Abe had historically made noises in the general direction that having nuclear weapons wouldn't be against the constitution as well. Very Japanese to have a face of nonproliferation and peacefulness while also positioning themselves with a full nuclear deterrent in their back pocket.

Edit: Also, those bad boys were simple fission bombs. Thermonuclear usually refers to fusion weapons. 6 month estimate would be a fission weapon boosted with tritium to increase the neutron flux and be a general very big bomb.