The Japanese adaptation of the French utility and paring knife. It is typically thinner and harder than Western utility knives, using the same premium steel as the maker's larger knives. A 150mm petty from a skilled Japanese smith handles like a small gyuto: thin, precise, and with a fine edge.
The 150mm sweet spot: a 210–240mm gyuto and a 150mm petty together cover essentially everything most home cooks need as a two-knife set. Blade height runs 25–35mm.
Primary tasks: in-hand peeling and precision board work, including trimming, scoring, precise vegetable cuts, and hulling strawberries. It is the knife within reach when the gyuto is too large.
Ideal steel: a petty is used for precision where a fine edge is directly perceptible, so high performance pays off: SG2, AEB-L, and Shirogami #1. It is the natural second knife for every serious cook who owns a gyuto.