Lacking in metals to mass-produce hand grenades in the vast quantities that would be needed against the projected Allied invasion of Japan, the Imperial Japanese Navy Technical Bureau developed a design for a cheap, easy-to-make grenade made of ceramic or porcelain materials.

Kilns famous for the production of traditional Japanese pottery, such as Arita, Bizen and Seto were pressed into service to manufacture these relatively crude weapons.

The Type 4 grenade had a fragmentation body made of terra cotta or porcelain materials.

A small, loose wooden block with an abrasive composition on one side was contained in the rubber fuse cover.

[1] Type 4 grenades were passed out in large quantities to civil defense organizations, such as the Volunteer Fighting Corps, Yokusan Sonendan, and to reservist organizations involved in preparations against the possible invasion of the Japanese home islands by Allied forces.