K.Yairi is a Japanese acoustic guitar maker based in Kani, a small town in the hills of Gifu Prefecture north of Nagoya. The company was founded by master luthier Kazuo Yairi, whose father Gi'ichi Yairi had worked as a luthier in the same region, and its factory carries on a largely hand-built approach to steel-string, classical, and nylon-string guitars. Necks are spoke-shaved, braces are hand-carved, and tops are voiced individually — a process Kazuo referred to as "listening with your hands."

The catalog spans dreadnoughts, orchestra- and parlor-style bodies, nylon-string classicals, electro-acoustics, acoustic basses, and compact travel guitars, along with more unusual projects such as the Ichigo Ichie (一五一会) co-developed with BEGIN. Signature construction features include the Direct Coupled Bridge and the use of carefully selected tonewoods. In the United States, the factory's steel-string output has long been distributed in partnership with St. Louis Music, with instruments also appearing under the "Alvarez Yairi" and "Alvarez by K.Yairi" names.

K.Yairi guitars have been played by a range of well-known artists including Paul McCartney, Carlos Santana, and Dominic Miller, and the brand is widely regarded among acoustic players for its hand-built construction and the longevity of its instruments, which are covered by a lifetime warranty from the factory.

K.Yairi has 7 products cataloged on Equipboard, including Steel-string Acoustic Guitars and Acoustic-Electric Guitars. Their gear is featured by 4 artists, with the strongest followings in Rock, Pop, and Stage & Screen. Notable users include Billie Joe Armstrong, Kanami Tono, and Shiori Kubo.