Some TMNT stuff really isn't for little kids.
Aka was the eldest child of the Dragon, a member of the Pantheon, and sister to Manmoth, Gothano, Chi-You, the Rat King, Toad Baron, Jagwar and Kitsune. Unlike most of her siblings, Aka was fond of humans and mutants, considering mutants to be the Pantheon's true children. Aka is friend to the human April O'Neil.
Aka expressed herself as a kind old woman. As the eldest surviving member of the Patreon, she took her position seriously and loved all her siblings as family.
But unlike most of the Pantheon, Aka also loved and respected humans, considering them to be the Pantheon's true children, and wanted to give humanity a fair chance of succeeding on its own merits. To this end, Aka had befriended and supernaturally aided April O'Neil, a human woman. However, Aka was clear that this fairness she sought for humanity was not a guarantee of their success but merely honoring their right to pursue their own destiny without unfair sabotage, accepting that humanity may still yet die out as a result of their own failures.
Because of Aka's decision to intervene in human affairs, her relationship with her youngest sibling Kitsune had been damaged. Aka and Kitsune ideologically differed on the fate of humans, with Kitsune eager to see humanity annihilated.
In the Teenage Mutant Ninja Turtles: Casey & April miniseries, April O'Neil meets Aka while she and Casey Jones are traveling in the southwestern United States. Aka explains to April some of the history and nature of the Pantheon, including the ancient struggle between its members and Kitsune's membership of the group. At the time, Aka is amicably neutral in human affairs.
In issue #60, when Kitsune has begun her rampage through Foot Headquarters in an attempt to depose Splinter as jōnin of the Foot Clan and seize Oroku Saki's remains, Aka appears to have a change of heart, giving April access to a supernatural artifact and incantation to temporarily suppress Kitsune's mind control powers. This turns the tide of the battle, forcing Kitsune to flee Foot Headquarters. The Rat King is surprised at his sister's decision to start taking sides.
Aka's decision was the cause of friction between the sisters in the Pantheon Family Reunion arc. Kitsune felt betrayed by her sister siding against her, though Aka made it clear that it was nothing personal against her youngest sister. When the Turtles were found to have infiltrated the Den of Delights, Aka pleaded with her siblings to show mercy to them, but was ignored.
In Shredder in Hell issue #5, Kitsune was at Foot Headquarters soon after Oroku Karai had wrested control of the Foot Clan from Splinter. She was covertly performing a ritual to resurrect Dragon, her father as well as the father of the rest of the Pantheon. The ritual required a sacrifice of divine blood to succeed. Kitsune's eldest sister Aka visited to witness the events of the ritual play out. But instead of sacrificing her own life, Kitsune turned on Aka, murdering her instead.
- Aka shares similarities with Onida, a supernatural character encountered by April O'Neil in the Mirage TMNT story White Horses. In that story, April takes a solo road trip to a remote island in the Pacific Northwest to contemplate what she believes is her imminent death. She meets and befriends Onida, a kind elderly Tlingit woman. Onida helps April deal with her existential crisis at having recently discovered she was not born human, but drawn to life by her father using a pen and a warp stone. At the end of the story, after parting ways with April, Onida turns out not to be human either, but the spirit of a deceased white horse who had assumed human form to encounter April.
- Aka is called "Red" as a nickname by her brother the Rat King. The word "aka" is Japanese for "red."
- Aka is the second Pantheon sibling Kitsune tried to eliminate, after Chi-You in Teenage Mutant Ninja Turtles/Ghostbusters. However, unlike Aka, Chi-You survived, albeit marooned in a parallel universe.