TOKYO, June 13 (Reuters) - Proxy adviser Institutional Shareholder Services Inc (ISS) has recommended that shareholders of Japan's Toyo Construction vote for six of nine director candidates backed by the family office linked to Nintendo's founder.

Yamauchi-No.10 Family Office (YFO), which holds 28.51% of Toyo Construction, is seeking to take the $687 million marine construction firm private.

The 1,000 yen per share takeover offer, however, has been resisted by the marine construction firm saying it undervalued the company even though it was higher than a 770 yen per share offer from an industry rival that Toyo Construction had endorsed at the time.

ISS said in a report that YFO's bid is "sufficiently compelling and reasonably certain," but the board's response "fell far short of providing reassurance that it had shareholders' best interest in mind".

"Based on the above analysis, we believe that a majority presence of the dissident nominees on the board is warranted to restore shareholder confidence and introduce the necessary governance improvements," ISS said.

ISS has recommended voting against six of 11 director candidates nominated by the company, saying that the presence of the remaining five nominees on the board would be needed to provide continuity.

A separate filing on Tuesday showed YFO has increased its stake to 28.51% from 27.19% previously. ($1 = 139.4800 yen) (Reporting by Makiko Yamazaki; Editing by Jacqueline Wong)