TOKYO, July 12 : Japan aims to raise the ratio of unlisted shares, real estate and other alternative investments in the portfolio of the Government Pension Investment Fund, the world's largest pension fund, the Nikkei said on Sunday.Finance Minister Satsuki Katayama, who has been trying to boost the weak yen, sparked a jump in the currency and government bond prices on Friday by saying the government aimed to steer the $1.8 trillion GPIF and other state pension funds to "substantially" increase investments in domestic assets.Alternative investments, as distinct from conventional assets such as listed shares and bonds, accounted for 1.7 per cent of GPIF's assets in March, far below the allowed 5 per cent cap.A government panel will soon compile a report stipulating the ratio will be raised