At the “Hoshikuso” (stardust) Pass in the Kirigamine Highlands, it used to be believed that fragments of twinkling stars had fallen onto the pass in the community. In fact, the “stardust” was the remains of obsidian that was mined by prehistoric Jomon people. The Hoshikuso Pass Obsidian Mines tells about the long-term obsidian mining throughout the Jomon Period. The mines were designated as a National Historic Site in 2001. Also, the Hoshikuso Pass Obsidian Mines and the Grimes Graves Flint Mines (Norfolk, UK) concluded “the world’s first twinning sites” treaty in 2016. An open-air museum that shows obsidian mining underground since 7,000 to 3,000 years ago will be opened in 2021.