Two weeks ago when China executed four Japanese nationals for drug-smuggling, the Japanese government's response amounted to little more than a shrug. The ruling Democratic Party of Japan continually expressed "concern" over the executions, with different officials qualifying this concern as being strong "public sentiment" in Japan against the execution of people for drug-related crimes. Japan, of course, has capital punishment, albeit only for certain types of murder, so it would have been difficult to protest the executions on humanitarian grounds, which is what the British government did when one of its citizens was executed in China for the same crime several months ago. The European Union does not have capital punishment.
The Japan Federation of Bar Associations expressed its own concern and criticized the DPJ for failing to prevent the executions. It's impossible to say whether or not a stronger protest would have made a difference, but according to the JFBA the government could at least have challenged the fairness of the men's trials. Chief Cabinet Secretary Hirofumi Hirano rejected this criticism, saying that the death sentences were carried out under the justice system of a foreign country.
It's obviously a touchy subject, made touchier by the fact that no one is willing to discuss capital punishment openly. The mainstream media treated the story as gingerly as the government did, sketching the particulars of the case without actually getting into the larger picture of China's war on drugs and its use of the death penalty to control undesirable social elements. They didn't even go into the backgrounds of the condemned, though the weekly magazines did, reporting what most people had probably already figured out. The executed Japanese were gangsters or drug mules, and the drugs themselves probably came from North Korea. The first man executed, Mitsunobu Akano, previously spent 28 years in Japanese prisons.