Koyuki Azumaya is a kunoichi who enters Natsumi's school as a transfer student. Drawn to Natsumi by what she only refers to as a "familiar scent", the two girls soon become best friends. While she does wear her civilian clothing when in public, she always keeps on her ninja uniform in case of an emergency. Her skills as a civilian and a ninja are exceptionally outstanding and her athletic ability even rivals that of Natsumi, making her one of the most physically powerful characters of the series. Despite having amazing powers and a troubled and strict past, Koyuki is very carefree, optimistic, and eccentric, but believes in what is right and protects her friends with all her might. Unfortunately, her tendency to utilize her ninjitsu maneuvers to accomplish the most mundane of tasks often draws much unwanted attention.
Koyuki's Keronian Parther
Koyuki's Keronian partner is Dororo. She finds and rescues a stranded Zeroro (now Dororo) from a boar trap and teaches him the ways of the ninja, which unwittingly leads to the dissolving of her ninja clan, giving her a chance at a real life in the city. Sharing many interests and the same positive attitude, Dororo and Koyuki have the most stable and cohesive relationship of the five Keronian/human child pairs. He trusts Natsumi to teach Koyuki to live a modern life.
In the Sequel to Sonic's Adventures of Kingdom Hearts. Koyuki appears in the World called "Beast's Castle" after Sergeant Keroro's world is destroyed by the Heartless lead by Pete and Malefincent. Koyuki appear to be still careful and comforts Belle as Sora and the other figure whats wrong with the Beast. Also Dororo is with her to assit her comforting Belle and calming Beast
Appearances in the Sonic Adventure Series
- Sonic's Adventures of Kingdom Hearts 2 (Debut)
- Sonic's Adventures of Naruto: Ninja Clash In The Land of Snow
- Sonic's Adventures of Naruto Shippedun: Homecoming
- Sonic's Advnetures of Naruto Shippedun the movie
- Sonic's Adventures of Rio
- Sonic's Adventures of The Wizard of Oz