Helmets were made at Saika in Kii province (Wakayama Prefecture) from the Muromachi period onwards under the prevailing influence of Western Arms and Armour. The work is characterized by heavy iron plates riveted together typically with decorative washers. There is usually a central plate riveted over the crown of the bowl serving both as decoration and added strength as with this example.
A shiinari [acorn-shape] eight plate helmet in the collection of the National Museum of Japanese History, Chiba prefecture, has similar leaves on the fukigaeshi, and also an upper face protection (as the present helmet once had) in the form of removable spectacles suspended from the peak (Morihiro Ogawa, ed., The Art of the Samurai, Metropolitan Museum of Art, (New York, 2009-2010), no. 48). The leaves of this tree have been identified with the winged tengu, or mountain sprites, whose skirts are often shown formed from leaves of this tree.
The inlaid characters on the helmet bowl refer to the six virtues of a gentleman and read Chi Nin Sei Gi Chu Wa [Knowing, Duty, Holiness, Principle, Fidelity, and Harmony].