The Bank of Japan loves buying exchange-traded funds. And the romance is spreading.

Trading in Japanese ETFs soared to ¥7.94 trillion ($69.8 billion) in January, double the volume of trading compared with January 2014 and a record, according to the Japan Exchange Group. This followed a busy 2015, when a whopping $38 billion of new money flowed into Japanese ETFs to bring total Japanese ETF assets under management to roughly $134 billion, according to Nikko Asset Management.