On his uncle’s orders, Hidetsugu also developed the town of Hachiman (now Omihachiman) below the castle and established it as a commercial hub. He invited merchants to live in the town and made it a tax- and toll-free zone free from regulation and the influence of trading guilds. He also ordered the digging of the Hachimanbori Moat, which served not only as protection for the castle but also as a canal for transporting goods. Later, however, Hideyoshi became suspicious of his nephew and Hidetsugu was disgraced. Two years later, he was forced to take his own life, and Hachimanyama Castle was abandoned. The town, however, continued to prosper and became an important center of trade and commerce.

Following Hidetsugu’s death, his grieving mother Tomo became a Buddhist nun and founded Zuiryuji Temple in her son’s memory. This temple was originally located in Kyoto but was moved to its present location on the summit of Mt. Hachimanyama in 1961.

The summit can be reached via a 4-minute cable-car ride on the Hachimanyama Ropeway. Parts of the stone ramparts of Hachimanyama Castle remain on the mountain, and Zuiryuji is located on the site of the castle’s main keep. Woodland trails lead from the cable-car station to the temple and to various observation points. Lookouts on the west side provide sweeping views over Lake Nishinoko, the Omihachiman wetlands, and the city of Omihachiman, while Lake Biwa and the Hira Mountains are visible from the north side. A stroll around the mountaintop, including a visit to the temple, takes around 30 minutes.