Ono and other Improvised Weapons

Ono refers to a hatchet, a very simple tool for cutting wood. As all the world knows, axes are almost just as good at cutting flesh and bone as they are at cutting wood. Axes and other weapons adapted from ordinary tools are mostly used by warriors of more humble backgrounds such as warrior monks, shadow warriors (ninja), and ashigaru. The samurai, a more dignified class, prefer high status weapons made by elite craftsmen.
It's not only axes. Shovels, sickels, hoes, and other ordinary tools can be converted into killing machines. Many citizens of Keikujo are not above doing such a thing. Though the samurai will not often use axes or sickles, they're quite partial to outsuchi (war mallets) and tessen (war fans).

5E D&D Rules

• Ono = Axe
• Kama = Sickle
• Kusarigama = Sickle + Flail (damage reduced to 1d6)
• Outsuchi = Maul (bonus damage to objects)
• Chigiriki = Flail
• Tessen/Gunbai = Club