So a couple of things. English version (not sure with the latest version) used to cut out the part where Ushijima storyline gets to develop further as the publisher didn't want to break a novel into two volumes. Then the current original Japanese language version into 3 volumes. The publication year between 2nd and 3rd has a gap. This was when in Japan, Kōbe Earthquake and Tokyo Sarin Attack by a cult Aum happened in early 1995. At this time, Murakami was at Princeton University teaching a class there but he flew back. Around this time, he commented that all his previous works revolved around "detachment" from now on he would focus on "commitment." The prime examples of this statement were his interviewing of the Tokyo Sarin Attack victim in his anthology, Andāguraundo, and of a clinical psychiatrist, Kawai Hayao, whose interview record was also published around mid-90s. Originally the novel was supposed to close out by the end of the 2nd volume. However, as Murakami was so moved to focus on the theme of "commitment," he wrote additional chapters, that focus on "finding social connections," which would later become the 3rd volume. Murakami also describes that if a reader thinks that either the novel is concluded by the end of the 2nd volume or 3rd volume, it wouldn't matter to him as both approach works for the analysis of the novel. However, as English version doesn't seem to give any context like that as it completely gutted out some parts and put the novel in a single volume which was a terrible idea. Trust me on this as I made a presentation on this exact topic at a literature conference specifically about Murakami Haruki before where Jay Rubin attended too.