Amid a storm of volatility in Japanese stocks, the Bank of Japan has kept the bond market a pool of serenity.

The Nikkei Volatility Index surged to 48.99 on Aug. 26, the highest since the disasters of March 2011, and was at 31.92 on Tuesday.

Since China¡¯s yuan devaluation last month, a similar gauge measuring fluctuations in Japanese government bond futures has averaged 2.69, below its one-year average of 2.90. Turnover in the JGB market last month dipped below the average over the past year, while Topix index volume surged to the highest in two years.