Why does PM Abe and the rest of the LDP think provoking South Korea is a good thing? Why does the average person in Japan accept without critical reflection that South Korea has no case to be made about Japan’s lack of contrition regarding forced labor and sex slavery? In the 40 years I have been here, anti-Korean sentiment has always been there just under the surface, and yet this nation has done little or nothing to confront its past.
This is not to say that South Koreans are not nationalistic; the similarities between the citizens of both nations are sometimes quite striking. And, despite a move to the left, South Korea continues to promote US militarism, just like Japan. The activists of Jeju and Okinawa have much in common, and-in fact-enjoy cooperative relations. Here are a few articles on that: Veterans for Peace Save Juju Now and a book review by a more neutral party.
Meanwhile, Asia Times reminds us that:
Japan-Korean relations slip to a new low, [that] Seoul-Tokyo relations have not been rosy since Prime Minister Shinzo Abe took power in 2012 – partly due to his support from Japan’s far-right, which itself utilizes anti-Korean sentiment.
The article further notes that, no doubt due to the rightist educational system:
A surprising number of people in Japan don’t seem to know much about atrocities committed by Japan during the Pacific War [and that] the group of right-wing nationalists, Shinto cultists, likely racists and historical revisionists that form Nippon Kaigi – and Abe’s hardcore base – have sought to rewrite Japanese history and textbooks for decades.
It also states that :
Abe has benefitted politically by tapping into a long-simmering prejudice against Korea, Koreans and the Zainichi – Japan’s ethnic Koreans. There’s even a word for it – Kenkan (嫌韓) (literally “Hate Korea”), but usually translated as anti-Korean sentiment.
And:
Though he rarely indulges in racism, Abe lets his underlings say things he cannot say himself. In 2014, he appointed to the head of the National Public Safety Commission a member of Nippon Kaigi, Eriko Yamatani, who was closely associated with Zaitoku-kai, a hate-speech group that targets Korean-Japanese.
In a now-infamous press conference, she refused to disavow the racist conspiracy theories of the group.
Here is an anti-Korean comic published in Japan.
Anti-Racist sentiment in Japan
As the photo shows, not all of Japan is rabidly anti-Korean. This was a recent demonstration in Shinjuku attracting several hundred people, both Japanese and Zai-Nichi. 
There are numerous acts of censorship taking place in Japan regarding Japan’s role vis-a-vis Korea, such as this now shuttered exhibit in Nagoya (due to intervention by Nagoya’s rightist mayor as well as Chief Cabinet Secretary Suga).
Meanwhile, in a bizarre article in the rightist Japan Forward, those doing the censoring are lauded as defenders of free speech.