* First Japan Post share sale since massive 2015 IPO
* Government to meet underwriters Monday - sources
* Sale to finance recovery from 2011 quake, tsunami (Adds details, context)
TOKYO, Sept 1 (Reuters) - Japan's government plans to sell shares in Japan Post Holdings Co as soon as this month, the first sale since the company's massive 2015 listing, a government source familiar with the deal said on Friday.
The finance ministry will meet with underwriters on Monday to discuss the sale, said this source and two other people familiar with the deal. Such meetings of an underwriter syndicate usually indicate the share offering process is nearing the final stages.
The size of the sale could not be immediately confirmed.
A ministry spokesman said he had no knowledge of the sale. A Japan Post spokeswoman said the timing of a share sale had not been decided and declined to comment further.
A share sale has been expected since the government picked six investment banks in March to underwrite the potentially large offering.
The finance ministry eventually plans to sell some 4 trillion yen ($36 billion) in the conglomerate, partly to fund reconstruction of areas in northern Japan hit by a catastrophic 2011 earthquake and tsunami.
Japan Post, which spans mail delivery, banking and insurance, made an unprecedented three-way initial public offering in November 2015. The government sold about $12 billion worth of shares in the holding company and its bank and insurance units.
The next sale could come quickly. When the government held a secondary sale of shares in Japan Tobacco Inc in February 2013, the sale launched six days after the meeting with underwriters.
The government, which now owns about 80 percent of Japan Post, expects to launch the secondary sale this month but might wait until October, especially if markets should become volatile, the government source said.
Shares of Japan Post jumped more than 40 percent in the weeks after the firm's market debut, but they have recently traded below the IPO price of 1,400 yen. The stock rose 0.4 percent on Friday to 1,371 yen. ($1=110.08 yen) (Reporting by Taiga Uranaka; Editing by William Mallard and Neil Fullick)