Conversation so far:
What is the main point of the article?
The processing of collective trauma soon became an important theme in Murakami's writing, which had previously been more personal in nature.
What was the trauma?
Murakami returned to Japan in the aftermath of the Kobe earthquake and the Aum Shinrikyo gas attack.
He came to terms with these events with his first work of non-fiction.

Question: What was his first non-fiction book?
Self-contained rewrite: What was Haruki Murakami's first non-fiction book?