Many thanks to Ayako for posting the link on twitter.
While Keanu Reeves was in London, he visited the MJ Group in St. John’s Square. This company specializes in the design, printing and binding of books.
The news page on their site has posted that Mr. Reeves has commissioned them to design, print and bind a limited edition of his book Side by Side. The MJ Group used the plural form of books. The graph accompanying the announcement seems to indicate that there will be more than one book.