A-sharp minor
Its relative major is C-sharp major.  Its parallel major is A-sharp major.  This is usually replaced by B-flat major, because A-sharp major's three double sharps in the key signature makes it generally impractical.  Exceptions include Chopin's Polonaise-Fantaisie in A-flat major, Op. 61, which has a short passage of about 6 bars actually written in A-sharp major, putting in the necessary double-sharps as accidentals.  This is part of a theme in B major, which modulates to A-sharp major for a little while.