In Buddhist temples throughout Japan, bonshō, or large bells – also known as tsurigane (hanging bells) or ōgane (great bells) – are used to mark the time and summon monks to prayer. Bonshō do not have a clapper; instead, they are struck from the outside using a handheld mallet or a beam suspended on ropes. The bells are usually made from bronze and ornamented with a variety of bosses, raised bands, and inscriptions. The earliest of these bells in Japan dates back to approximately 600 CE.

Bonshō are cast in a single piece using two molds, a core and a shell, using processes that have remained largely unchanged since the Nara period (710–794). The core is constructed from a dome of stacked bricks made from hardened sand, while the shell is made using a large, flat, wooden board known as a strickle board. Shaped like a cross-section of the bell, the board is rotated around a vertical axis to form the clay into a mold. Inscriptions and decorations are then carved or pressed into the clay. The shell fits over the core, creating a narrow gap into which the molten bronze is poured. The ratio of copper to tin, as well as the speed of the cooling process, affect the bell’s tone. After the metal has cooled and solidified, the bell is removed by breaking the mold. A new mold must be created for each bell.