Sayoko Shiki

Sayoko Shiki (志岐 小夜子) is the Operator of Nasu Unit.

Appearance
Shiki has chest-length, straight black hair with two locks that fall over her ears and an uneven fringe that covers her right eye. Two green hairclips prevent her left eye from being obscured too. The rest of her hair is gathered behind her headphones. She has large, brown eyes which she keeps perpetually half-open. She has a tendency to slouch. She normally wears casual, comfortable clothes such as a zipped sweater over a light-colored shirt. In her trion body she wears the standard Operator uniform.

Personality
Shiki is a hikikomori. In the past she lived on the scant provisions sent to her by her family, but after joining Border she began to shop online by herself. Her condition seems to have improved since, as even though she does not show up to strategy meetings at Nasu's house in person, she leaves her own home for rank battles and Border duty. She is not good at dealing with the opposite sex, especially older men, to the extent that it affects her life. On the other hand, with her teammates she comes across as a smart girl who speaks confidently and occasionally playfully in spite of her usual reclusiveness.

Rei Nasu
As with her other teammates, Nasu appears to be friends with Shiki, whom she calls by a nickname; the Operator, on the other hand, addresses Nasu by her surname as a sign of respect.

Yūko Kumagai
Kumagai is the one who scouted Shiki and brought her on as the unit's Operator. The two seem to be the most active while brainstorming the unit's strategies. They appear to be close, as Kumagai addresses Shiki by her first name.

Akane Hiura
Shiki and Hiura are friends as well as teammates. Shiki has a habit of teasing Hiura about her tearful outbursts and addresses her by her first name.

Background
Shiki joined Border roughly two years before Yūma Kuga and Chika Amatori. She has been a hikikomori for an unknown amount of time, and she lived on pickled kelp and water sent to her by her family when Kumagai scouted her. Since joining Nasu Unit she has her financial situation in check and has taken to shopping online.Shiki is the one who designed the uniform of Nasu Unit, which earned her the praise and respect of some male agents.

B-Rank Rank Battles Arc
On the eve of her unit's match against Tamakoma Second and Suzunari First, Kumagai and Nasu meet at the latter's house to discuss a strategy while Shiki corresponds through her computer. They discuss the footage of Yūma Kuga's solo matches against Kō Murakami and his abilities compared to his teammates'. Kumagai is more concerned about Suzunari First, against which they have lost six times in a row. Shiki remembers that Suwa Unit defeated the team by remaining in Gunner range, so they decide to base their strategy on Nsau and pick a stage that facilitates it. When she joins them, Hiura tells them that she was unable to dissuade her parents from moving after she graduates middle school, prompting Nasu to swear they will climb up the ranks before she has to leave.

The following day the four members of Nasu Unit recap their strategy minutes before the match. Once again they resolve to advance in the ranking. After the match starts and the bridge is destroyed by Chika, Shiki relays the information to her captain and tells Hiura to hide. When Taichi Betsuyaku snipes at Nasu, Shiki sends her a 3-D image map to help her shoot back. She observes anxiously when Hiura decides not to bail out but to face Yūma head-on. When Nasu switches to cornering Tatsuya Kuruma with her mobility, she instructs Shiki to keep an eye on the members of Tamakoma Second. Shiki congratulates her when the match is over. The four members of the unit resolve to keep trying to reach theupper tier of B-rank.

Abilities
As the Operator of a moderately successful B-rank unit, Shiki is probably a competent multi-tasker. She is very proficient at digging up information with her computer, a skill which she uses to aid her teammates in creating strategies. She is very active in the latter process, displaying good analytical skills and insight. During combat she may on occasion assist Kumagai in directing Hiura. She is competent at operating her terminal, which she demonstrated by rapidly analyzing the trajectory of Betsuyaku's shot and creating a 3-D map from Nasu's perspective. In addition, she has unusually high trion reserves for an Operator, which are not only the most abundant of any known Operator, but are also higher than those of the majority of Border combatants.

Trivia

 * Shiki likes games, water, reading, and online shopping.
 * She is the only member of her unit not to share her voice actress with another character in the anime.
 * Her voice actress was not revealed together with her teammates', but only when Shiki appeared in the anime.