One of the unique theme of the Shirataki National Geopark is that we can learn about the eruption process of obsidian lava flow. The eruption of viscous lava formed the obsidian rock. Especially, we can find there the red colored obsidian, which is formed by oxidization of magma. The local people call it as “Hana-Tokachi”. We can walk on the trail filled with the beautiful obsidian. Shirataki Obsidian was the essential material to survive for ancient people lived about thirty thousand years ago. In Shirataki National Geopark, we can learn about the volcanic eruption which formed obsidian and the connection between obsidian and the humanity who used it as stone tools.