Bronze 'Four-leaf clover' mirror, Eastern Zhou Dynasty, 4th century BCE. Diameter 10.1 cm; weight 211 g. Catalog 39 © 2026 Hyogo Prefectural Museum of Ancient Bronze Mirrors

The thin mirror body, the spoon-shaped curved rim, and the beveled edges on the upper surface of the periphery are typical features of the late Sengoku period.

The entire back surface displays a feather-like pattern, the knob is a three-pronged knob (a knob with three parallel lines), and the perimeter is surrounded by a grid with leaf patterns on its four sides. The feather-like pattern is arranged as a unit pattern grouped into squares. It is the simplest expression among the feather-like patterns that developed in the late Sengoku period.