Japan's militarist nationalists never really went away after World War 2, they just bided their time and waited for the day when they would be able to return to power. At last, they have done so; Shinzo Abe, the current prime minister, is the grandson of Nobusuke Kishi, an important WW2 nationalist whom the U.S. initially imprisoned for war crimes, and later let out (probably to fight against Communism), and who himself because prime minister of Japan in the 50s. It's not clear whether Abe himself thinks his ancestors did anything wrong in the militarist era, but many of his political appointees clearly do not think so. Naoki Hyakuta, whom Abe appointed to the board of governors of Japan's public broadcaster, claims that Japan committed no atrocities in World War 2 and was acting to free Asia of Western colonialism. Another board member described the Japanese Emperor as "a living God".
The return of the rightists seems to lend credence to the claims of China and Korea that Japan as a country has not properly atoned for World War 2. If people who think Japan was on the side of good can gain national power, then the country as a whole must agree with them...right? Sure, Japan has made a litany of apologies for World War 2, and even offered some monetary reparations. But mustn't those have been pro forma gestures to appease the United States, rather than heartfelt expressions of regret?
Actually, I don't think this is the case. Japan's rightists have power now, but that seems due much more to Japan's dysfunctional political system than to any general militarist/nationalist sentiment among the Japanese people and elites.
To see this, look at the votes cast on the 1995 "Fusen Ketsugi" resolution. That resolution was an apology for World War 2. The text read:
The House of Representatives resolves as follows:
On the occasion of the 50th anniversary of the end of World War II, this House offers its sincere condolences to those who fell in action and victims of wars and similar actions all over the world.
Solemnly reflecting upon many instances of colonial rule and acts of aggression in the modern history of the world, and recognizing that Japan carried out those acts in the past, inflicting pain and suffering upon the peoples of other countries, especially in Asia, the Members of this House express a sense of deep remorse.
We must transcend the differences over historical views of the past war and learn humbly the lessons of history so as to build a peaceful international society.
This House expresses its resolve, under the banner of eternal peace enshrined in the Constitution of Japan, to join hands with other nations of the world and to pave the way to a future that allows all human beings to live together.This resolution was approved, but almost half of the members of the Diet abstained from voting! This means they didn't believe Japan should apologize, right?
Actually, no. A large number of the abstainers wanted an even stronger apology. From Wikipedia:
Out of 502 representatives, 251 participated in the final vote on the revised resolution, and 230 of them supported the resolution; 241 representatives abstained from voting; 70 absentees belonged in one of the three parties in the coalition cabinet that sponsored the resolution (Japan Socialist Party, Liberal Democratic Party, and New Party Sakigake).
14 members of the Japanese Communist Party voted against the resolution because they wanted much stronger expressions in the resolution.
50 members of the conservative Liberal Democratic Party did not participate because the expressions in the revised resolution were still too strong for them.
14 members of the Japan Socialist Party did not participate because the expressions were not strong enough for them.
141 members of New Frontier Party abstained from voting, some of whom wanted stronger expressions.So if we total up those who voted against the bill with those who abstained because the apology was too strong for them, we get at least 71 out of 502 representatives, or 14%. Now, some of the New Frontier Party might also have believed that the apology was too strong, so let's conservatively assume that half of them, or 71/502, believed this; that brings the total percentage of Imperial apologists to 28%. 14% is not that big of a bloc, but 28% is a pretty substantial minority.
But either way, we see that a majority of Japanese politicians supported a World War 2 apology in 1995. Now, 1995 may have been an unusually liberal moment for Japan; perhaps the electorate voted for a less nationalist Diet than they would prefer?
Actually, polls suggest that the Japanese public is less nationalistic than its politicians. This supports the notion that it is Japan's dysfunctional political system, which is dominated by old political families, that keeps the thin flame of militarism/nationalism alive. At the elite level, there is a non-trivial minority of Japanese bluebloods who thought WW2 was the right thing to do. But they are definitely a minority, and their attitude is not shared by the Japanese public. (Caveat: Among young people, right-wing attitudes may have become more common in recent years.)
In other words, the Chinese and Korean perceptions of an unrepentant Japan are not very accurate. But Japan itself has a serious problem - it finds itself ruled by a right-wing fringe element. Unless Japanese people can shake off their traditional attitude of political powerlessness, apathy, and ennui, they will increasingly find their country being moved in a direction they don't like. Freedom ain't free, fellas.