ESG investing is so popular in Japan that even Buddhist monks are getting into it.

One of the new investors is Tokuunin, a Zen Buddhist temple in central Tokyo. The religious group wanted to make more money for building repairs and maintenance over the coming decades, so it bought 40-year social bonds sold by the University of Tokyo, according to Yuzan Yamamoto, its chief priest.

"At a time when we can barely get any returns from long-term savings, we’re happy that we can contribute to helping society while earning enough returns to cover inflation,” Yamamoto said.