Aikata is a term used in the fields of classical Japanese music and dance. The term is used as a category name of musical composition in the field of classical Japanese music, while it means a partner when being used in classical Japanese dance.
By extension, the term has come to be used for one's duo partner in manzai (a comic dialogue), which has led some people to refer to their girlfriend/boyfriend by the term aikata.
Aikata in classical Japanese dance
A comprimario is referred to as aikata in kabuki stories performed by two or more actors. In the case of joruri (dramatic narrative chanted to a shamisen accompaniment), the aikata means a shamisen player accompanying tayu who perform a dance.
Aikata in classical Japanese music
In the field of kabuki, the term aikata refers to instrumental music which is played, accompanying the movements of actors, including entrances and exits, in kuromisu (a slatted room at the stage right) (geza music).
This kind of music includes those generally called 'XX Aikata' as well as those having proper names such as 'Taimen Sanju' and 'Seigyo.'
Pieces of music of debayashi (an onstage ensemble) above a certain length (interlude) are also referred to as aikata, each of which is usually given a title like 'Azuma Hakkei' (The Eight Views of the East) and 'Tsuru Kame' (Crane and Turtle).