Niko Kuna

is a veteran researcher who works for the S.R.D.I., which is tied to the 12th Division of the Gotei 13.

Appearance
When she joined the S.R.D.I., she had green eyes and short black hair that reaches to the top of her neck. A chain was wrapped around her head and hung on the left side of her face. A small tuft of hair hung from the bottom of the chain. She wore large square-rimmed spectacles and the standard Shinigami shihakushō under a white lab coat. A hundred years later, the chain around her head is gone. She has a small chain hanging on either side of her head with a small tuft of hair suspended from each of them. Her hakama no longer extends below her thigh-length lab coat.

History
She joined the Shinigami Research and Development Institute upon its inception by Kisuke Urahara and has remained in its service since.

While she was working in one of the S.R.D.I.'s labs, the Reiatsu of members of the Ninth Division disappeared. Urahara came rushing into the lab and asked where Hiyori Sarugaki was. She told him that Hiyori had already left for the Ninth Division's location. Later, when Urahara lies back in his office distracted over what to do, she comes to the door and wishes him goodnight as she goes home. Leaving, she gives him a worried glance before walking away sadly.

Soul Society arc
When Rukia Kuchiki is arrested in the Human World, she brings Rukia's Gigai to the lab as requested. When one of the other researchers asks who made the Gigai, she suggests that it ought to have been Akon, but notes that he does not seem like someone who would make that kind of Gigai. As they study it, Hiyosu and Akon look startled. She asks what it is and Akon tells her the Gigai was not made by anyone that is still in Soul Society.

Arrancar arc
Kuna is present when the researchers are gathered by Captain Kurotsuchi to be informed of Captain-Commander Yamamoto's order that they make it easier for captains and lieutenants to release their limiters against the Arrancar in the Human World. Along with most of the others, she refuses to volunteer for the trip to the Human World and reacts with shock when Rin Tsubokura volunteers for the mission.

The Thousand-Year Blood War arc
She greets Akon when he returns to the S.R.D.I. after the Wandenreich invasion and asks him if he has recovered. He says that he hasn't recovered, but it's not his style to lie in bed, he then asks her where the captain is. Kuna replies that the captain hasn't left his room since the battle. Akon is surprised that the captain has been in his room for that long with the surveillance bugs shut off. Akon then switches on a camera to the captain's room, and they're both shocked when they see what's going on in there. When the Seireitei replaced by the Wandenreich, Kuna is present in the SRDI as it is supplanted with Quincy architecture by the shadows. As the Sternritter Askin Nakk Le Vaar explains the nature of the 'shadows' and how the Wandenreich had always been in the Seireitei, she witnesses Mayuri and Nemu emerge from an unseen room and is surprised at their bizarre clothing.

The following day, after most of the Gotei 13 have left for the Royal Realm, Kuna accidentally discovers the remains of the Nemuri Project, which prompts Akon to explain the history of the project to her.