Prime Minister Shinzo Abe's popularity continues — the latest Nikkei and TV Tokyo survey shows his approval rating at 66 percent, his Liberal Democratic Party's victory in the Upper House election seems highly probable, "Abenomics" is still on course, and even medium-term economic growth seems possible if — and this is a big "if" — his promised reforms actually materialize.

No major single issue has threatened this outlook so far. But one is looming on the horizon: the Constitution.

Ever since its founding in 1955, the LDP has been trying to rewrite the pacifist Constitution, which was effectively drafted by the United States back in 1946. Abe has long championed the issue, which includes war-renouncing Article 9.