mythical item- after the beatimg tundra shogun he has a 1% chance to drop the ZeRo katana (note: the ZeRo katana has the ability of -subzero- meaning it freezes the target
11.6 Japanese Swords 1.6.1 The Myth and the History of the Japanese Sword
20 Types of Legendary Japanese Swords: The Ultimate Guide | Knife Pulse