* Mitsui plans to increase yen bonds by Y30 bln in H2
* No.5 insurer remains cautious on high-volatility assets
* Will speed up buying superlong JGBs if their yields rise
By Satomi Noguchi and Takefumi Ito
TOKYO, Oct 20 (Reuters) - Japan's Mitsui Life Insurance said on Tuesday it may shift funds to yen bonds from hedged foreign debt in the second half of the fiscal year to March if yields on Japanese government bonds rise.
Japan's top nine insurers held around $1.6 trillion in assets as of March 2009 -- about the size of Brazil's economy -- and investors keep a close watch on their plans because their investments can affect financial markets.
Mitsui Life, the nation's fifth-largest life insurer by assets, said matching its assets to its yen-based liabilities is a high priority and that it plans to increase yen bond holdings by a net 30 billion yen ($330 million) in the October-March second half.
Toshiya Yoshimura, head of Mitsui Life's investment planning department, said in an interview with Reuters that the company is keeping its cautious stance towards high-volatility assets including emerging market equities.
Mitsui slashed its holdings of overseas shares and other illiquid investments like hedge funds and securitised products in the last fiscal year to March 2009 amid the financial crisis.
"Investments in hedge funds or emerging markets involve a high degree of volatility. Those kinds of assets are hard for us to touch at this point because the risks associated with them are difficult to grasp," Yoshimura said.
Mitsui Life managed 6.7 trillion yen ($74 billion) of assets on behalf of policy holders as of March 2009, and held 381 billion yen of foreign bonds.
It said all of its current foreign bond holdings were currency-hedged with half denominated in dollars and half in euro, after it bought some euro-denominated bonds in the first half.
The company expects the dollar to trade at 90-105 yen for the rest of the fiscal year and sees it at 95 yen at the end of March. It forecast that the euro would trade at 120-140 yen for the next half and 130 yen at year-end.
The dollar traded at 90.10 yen on Tuesday, above an 8-1/2-month low of 88.01 yen hit earlier this month. The euro stood at 135.00 yen.
Mitsui Life said it aims to purchase superlong JGBs and will speed up this buying if their yields return to levels seen in June and August.
The yield on 20-year JGBs rose to 2.2 percent in June, its highest in eight months, while the yield on 30-year debt climbed to 2.36 percent in August, a 10-month high.
The company forecasts that the 10-year JGB yield will be at 1.2-1.6 percent in the second half.
Mitsui Life sees the Nikkei share average moving to 9,000-11,000 in the second half and said that it may cut Japanese stock holdings slightly in the same period. (Editing by Joseph Radford)