These artifacts were accidentally found during the construction of a pond in 1918. According to the record of an interview with the discoverer, both of them were found at 60 cm below ground.
The dotaku is small in size and has a rare pattern structure where the A side has a flowing water design and the B side has a kesadasukimon design (a pattern that looks like a priest's outer garment). Among the four development stages of dotaku, this one belongs to the second stage (gaientsuki-chushiki). On the other hand, this bronze mirror, different from Chinese Han-style mirrors, has two hand-drum-shaped knobs placed on one-side. The back of the mirror comprises a mirror rim, an outer section, an inner band and an inner section. The cross section of the rim is semi-cylindrical in shape and the entire surface of the mirror is concave. The concave surface is one of the typical characteristics of the second stage bronze mirrors. On the back of the mirror, an elaborate geometric pattern is created via casting. This is a delicate and geometrically beautiful mirror. While many mirrors of this type have been found centering on the Korean Peninsula, Mongolia and the northeastern part of China, they have been found only in ten ruins in Fukuoka, Saga, Nagasaki, Yamaguchi, Osaka, Nara and Nagano in Japan (a total of 11 mirrors).
When these artifacts were found, the creation year of bronze mirrors was generally understood since tachusaimonkyo (mirrors with multiple knobs and geometric patterns) had been found together with bronze swords and pikes among the Ipsil-ri Relics in Korea and the Kajikurihama Relics in Yamaguchi. However, the creation year of the dotaku was not clearly established. This is a very valuable example in that a dotaku and a tachusaimonkyo were found together for the first time. This example has been treated as an important basic material not only for the establishment of the creation year of the dotaku, but also for the study of burial of bronze mirrors.