The ono (斧) (historically wono, をの) or masakari is the Japanese word for an "axe" or a "hatchet", and is used to describe various tools of similar structure. As with axes in other cultures, ono are sometimes employed as weapons. Many existing examples of this particular weapon are associated with the sōhei (warrior monks) or yamabushi, who also adapt other agricultural tools as weapons, although samurai are also pictured as using ono in woodblock prints. Ono that were specifically designed for military use are of extreme rarity. The weapon version of the ono is described as having "a very large head with a very convex cutting edge and a large scroll-shaped peen opposite it. It has a sheath covering only the edge of the blade. The entire length is nearly six feet".
- The ono is the weapon of choice for Kintarō, a Japanese folk hero.
- Ermac from the Mortal Kombat series uses a black and silver ono in his weapon style, though the style is simply titled Axe.
- In BattleTech, The Draconis Combine Mustered Soldiery nickname the Clan battlemech "Warhawk", the Masakari.
- Mega Man 10 enemy Merserker is based upon this weapon.
- The For Honor Hero "Hitokiri" uses the weapon in game.
- One of Luffy's attacks, Gomu Gomu no Ono, is named after it.
- Ratti, Oscar; Westbrook, Adele (1991). Secrets of the Samurai; A Survey of the Martial Arts of Feudal Japan. C. E. Tuttle. p. 322. ISBN 978-0-8048-1684-7.
- Mortal Kombat: Deception and Mortal Kombat: Armageddon