In France, it says "no turning right / left." In Japan, we say "duty to go straight or turn right / left". QED.
Edit: Some people have reported to me that this panel was also famous in France. This is quite true. This little note is mainly to highlight the fact that the Japanese have a strong tendency not to say "no" and this is also reflected at the level of traffic signs as "no turn right / left" do not exist in Japan.