At this point, whether they plagiarized or just merely paid homage in a clumsy manner is kind of immaterial when there's so much else about this game that's just...ew.
Honestly, it's very naive to describe what's happening as plagiarism. The game appears to contains hundreds of lines of dialogue, and yet only a handful of those pertain to the Murakami book and it's actual plot line is not lifted from the work that's allegedly being plagiarized. It'd be like claiming a movie plagiarized The Terminator for having a character saying "I'll be back" while not being about time traveling cyborgs.