TOKYO, Jan 15 (Reuters) - Less than half of companies on the Tokyo Stock Exchange's (TSE) top section have answered a bourse call to disclose plans to improve capital efficiency, the TSE said on Monday, as it released for the first time a list of those who had complied.

The list - which notably did not include some of Japan's biggest and most influential companies, such as Toyota Motor and SoftBank Group - marks the culmination of a push the bourse made last March to nudge firms to improve governance and investor returns.

Some 40% of the 1,656 companies on the exchange's prime section have publicly disclosed plans, while another 9% are considering such measures, the bourse said.

Optimism about the initiative, which can include measures on returning more money to shareholders or shedding non-performing assets, have helped propel the Tokyo market to its highest level in more than three decades. Investors are now hoping to see long-term change in Japan.

"I applaud the TSE's initiative, but I would not read too much into these disclosures until we look at their impact later on. There is a big difference between saying you have a policy to consider cost of capital, and actually implementing it," said Nicholas Benes of the Board Director Training Institute of Japan and a veteran governance expert.

"For many firms, the best litmus test will be whether they move to sell non-performing business units or not."

The list, which the TSE will update monthly, will effectively put pressure on companies to fall in line and disclose their plans, experts said. That could help spur the reform of a market where nearly half of listed firms trade below book value, they said.

The number of firms with disclosed measures shot up from the TSE's tentative survey in July, which saw only 20% of prime-listed companies had made such disclosure.

The TSE has set no deadline, saying it is not asking for quick fixes but long-term strategies to improve valuations.

The spotlight is now likely to be on companies not on the list rather than those on it. The absence of Toyota is notable, as it is Japan's biggest company in terms of market capitalisation and influence.

Toyota said its plan for "growth with stakeholders" was effectively the same as what the bourse was requesting.

The TSE's move has made companies scramble to review the use of capital, sparking a slew of share buybacks, unwinding of cross-shareholding and some management buyouts that take companies private to escape burdens of being listed.

Morgan Stanley MUFG Securities in a report to clients last week said those considering measures may surprise on the upside with capital return announcements during the upcoming earnings results season, adding that the TSE's reform initiatives are "a key aspect of our positive view on Japanese equities." (Reporting by Makiko Yamazaki, Brigid Riley, Anton Bridge and Maki Shiraki; Editing by David Dolan and Christopher Cushing)