Kiyal Bachika is the youngest of the Black Siblings, a group of siblings who join the main characters in their fight. As the most mischievous member of her family, she has a spirited and somewhat childlike personality that is visually marked by a single fang protruding from the left side of her mouth. Her name is derived from the Japanese word yaruki, which means willingness or motivation, reflecting her eager nature.

In the early stages of the conflict against the Beastmen, Kiyal works alongside her sister Kiyoh in the control room of the massive gunman known as Dai-Gurren. As the war progresses, she transitions from a support role to a more active combat position, taking to the front lines as the pilot of a customized gunman she names the Kiyalunga. This machine is notable for its ability to transform into a shield and a lance, which can then be wielded by her older brother Kittan in his own gunman, the King Kittan.

Following a significant time skip, Kiyal is shown living with her sister Kiyoh and brother-in-law Dayakka. During this period, her youthful and unguarded nature persists, as she openly and childishly criticizes the controversial political actions taken by the character Rossiu against her friend and comrade, Simon. Her loyalty to her friends and family is a defining trait, and she provides both support and a source of unfiltered commentary within the group. Her closest relationships are with her siblings, including her brother Kittan and her sisters Kiyoh and Kinon, as part of the tight-knit Black Siblings unit. Kiyal is depicted as an energetic and spunky individual whose quick thinking and determination make her a valued ally, even when she is not serving as a primary frontline fighter. Her skills are centered on her ability to pilot her gunman, the Kiyalunga, in coordination with her brother's machine. In supplementary material, it is also revealed that she possesses a sharp business sense, becoming the president of a successful company later in life.