Here is the link to an article by Lila Shapiro about the cover on vulture.com. She writes: "[W]hen readers walk into a bookstore and see a freshly printed hardcover copy of one of his U.S. editions, they often find themselves inexplicably drawn in by the gravitational force of an obscure astronomical entity." According to Shapiro, this is "mostly because of Murakami's writing" but also "because of the art of Chip Kidd." The article also quotes Kidd as saying that, "I'm translating what I think he's trying to get across. ... In that sense, it's very presumptuous on my part."
The article describes how this final cover design is in fact a second design. Without having read the book (as the English translation was not yet available), Kidd had first designed a different cover (pictured below). However, Murakami asked him to rethink the design once the English version was made available to him. This was apparently the first time in their 25-year-long working relationship that he redesigned a cover at Murakami's request.
Below on the left is the image of the first draft, which seems much more disturbing than the final draft, perhaps because it refers more literally to the "killing" in the title. Kidd himself apparently realized that it was "too lurid." So he came up with a new design for the jacket, which apparently features a hole in the middle. Under the jacket the blue of the cover "gives way to dark night." Below on the right you can see the image under the jacket. For more details on the potential meaning of the design and the designer, you can read the article here.
The novel will be out in English translation by Philip Gabriel and Ted Goossen on October 9th and can already be preordered on Amazon.