The Hoki Ichinomiya Kyozuka (sutra mound) was believed to be the grave of Shitateruhime no Mikoto in ancient times, which led to repeated looting. In 1915, several people dug into the mound without permission and uncovered a copper sutra cylinder containing sutras, a gilt-bronze Buddha, a bronze mirror, a cypress fan, daggers, sword fittings, jade, copper coins, and lacquerware. The copper sutra cylinder, 42 cm tall, featured an inscription of 15 lines with 237 characters. It acted as a kind of time capsule, intended to preserve the sutras of Buddha's teachings for future generations. The excavated items were designated National Treasures in 1920 and are currently on display at the Tokyo National Museum. The sutra mound itself was also designated a National Historic Site in 1935.