The Bank of Japan (BOJ) headquarters in Tokyo, Japan, on Tuesday, March 19, 2024. The BOJ ended the most aggressive monetary stimulus program in modern history, scrapping the world's last negative interest rate and a raft of unconventional tools, while leaving the course of additional hikes unclear. Photographer: Akio Kon/Bloomberg 未知の水域を過去20年に何度も航行してきた先進国・地域の中央銀行が、新たな難所を迎えている。主要中銀が共同で量的引き締め(QT)に動