Kiyal Bachika, the youngest of the orphaned Beastman-hunting Black Siblings alongside Kittan, Kiyoh, and Kinon, served initially in the Dai-Gurren battleship's control room during the Beastman War before transitioning to frontline combat. She piloted the customized Gunmen Kiyalunga, which transformed into a shield and lance wielded by her brother Kittan in his King Kittan during battles, including the assault on the Spiral King's fortress, Teppelin.

After humanity's liberation, Kiyal lived in Kamina City with her sister Kiyoh and brother-in-law Dayakka. During this time, she participated in discussions concerning Simon's marriage proposal to Nia Teppelin. Alongside Kiyoh, Kiyal questioned Nia's initial rejection, urging her to reconsider based on the emotional intent behind Simon's words rather than a literal interpretation.

When the Anti-Spiral's Humanity Annihilation System activated, triggering Mugann attacks and a looming lunar collision, Kiyal was present at Kiyoh's childbirth in the hospital. She evacuated with civilians to the Arc Gurren as the attacks intensified. During the conflict, she witnessed her brother Kittan's heroic sacrifice to disperse the Sea of Despair. Kiyal later attended Simon and Nia's wedding, experiencing the emotional aftermath of Nia's disappearance following the Anti-Spiral's defeat.

In expanded media like the manga adaptation, Kiyal's role was significantly increased compared to the anime. The Parallel Works OVA segment "Kiyal's Magical Time, Three Minutes Before" featured her in a magical girl scenario during her pre-teen years. Her name originates from the Japanese word "yaruki," meaning "willingness."