here is Ayaka's ref sheet! bio below (and yes, a crossover OC bc im multifandom XD)
NAME: Ayaka Torakuma "The Lone Wanderer of Youkai Mountain"
ABILITY: Can transform into a oni and tiger
Ayaka is an oni who resides in Youkai Mountain. She watches over to check for any lost humans and youkai and helps them out the mountain.
She's solitary in nature, preferring to have her own peace.
Her personality can be described to be empathetic, composed, and direct, though her directness may scare other youkai and humans, and she would sometimes go off on her own.
She wields a Naginata named "Tiger's Fang".
Ayaka is also one of the Oni Devas, being it's youngest member. She is close with Yuugi Hoshiguma, who she sees as her older sister. She is also close with Suika Ibuki and Kasen Ibaraki.
She participated in the Genso-Lunar War, and is how she got her scar.
(Below includes how her story connects to Kingdom Hearts)
When Youkai Mountain was attacked by Heartless, Ayaka stepped forward to defend it, only to get her heart stripped away by a Heartless.
When her body was about to fade, Yukari Yakumo helped putting Ayaka's body in limbo. Yukari used her border powers keep Ayaka from fading, and gave her a fragment of her soul for her body to stay intact and to heal.
This in turn gives her Nobody, Kayaxa, her Border Manipulation Powers, but only a small fragment of it.
After being recompleted sometime prior to Kingdom Hearts 1, she meets up with Sora during the events of Kingdom Hearts 2 and acts as both his mentor and guardian as her Nobody was once part of Organization XIII.
During the events of Kingdom Hearts 3, she meets up with Saix before the New Keyblade War after he meets up with Axel/Lea and tries to convince him to change sides (but ultimately fails to do so).
After Kingdom Hearts 3, Ayaka and Isa, now both recompleted, meet once more and their bond grows closer than of their Nobodies.