TOKYO: The yield on Japan's 10-year government bond dropped below zero on Tuesday, in a first for a G-7 country as panicked investors flee a bloodbath on equity markets. The note’s effective return slipped to minus 0.005 per cent in the afternoon, continuing a downtrend sparked by the Bank of Japan's surprise move last month to slap a negative interest rate on some commercial lenders’ deposits. Before the unexpected decision, Japan’s 10-year bond was paying a yield of about 0.2 per cent, similar to the current payout on a comparable German government bond.