Iron and diamond rocks are scattered throughout Nippon in Ōkami. Despite looking similar in shape to their gray counterparts, these rocks cannot be Power Slashed until the technique is upgraded. Iron rocks are an orange-black color, resembling rusted iron, and Power Slash 2 is required to break them. Diamond rocks are purple-colored and have diamond crystals on them; only Power Slash 3 can break them. They may also be breakable by tackling them after acquiring the Hardhead Dojo Technique and the aforementioned upgrades of Power Slash.