Some are turning to his scholarly titles for clues, but they are proving hard, and expensive, to come by. A copy of his 2005 book "The Fight Against Zero Interest Rates", which has a recommended retail price of 1,700 yen ($13), was listed as having sold at 29,800 yen ($225) on e-commerce platform Mercari on Monday.
Other copies were being offered at prices as high as 35,288 yen ($266).
The book's publisher, Nikkei BP, told Reuters it was considering plans to reprint as well as to make the text available as an e-book. Only 8,500 copies were printed in the previous run and had all sold out, the publisher said.
Another Japanese-language title he wrote in 2017 was ranked as the best-selling e-book in the finance section on Amazon's Japan site on Monday. Hard copies of some of his other publications were sold out on the site. Prime Minister Fumio Kishida is due to confirm his pick to succeed outgoing Governor Haruhiko Kuroda on Tuesday. Ueda is something of an unknown quantity for many in the markets, economists and analysts said.
The yen initially jumped on Friday on expectations that he could phase out ultra-loose policy earlier than expected, but quickly trimmed gains after he said in a television broadcast that current BOJ policy was "appropriate". Ueda likely would not rush to overhaul loose policy and would instead let economic data guide the exit timing, said Tetsuya Inoue, Ueda's staff secretary when he was a central bank board member, told Reuters in an interview on Monday. ($1 = 132.4500 yen) (Reporting by Kantaro Komiya and Satoshi Sugiyama; Writing by John Geddie; Editing by Robert Birsel)
