Nagase appears like most Snowy Neko officers — long white hair, grey eyes. She is shorter and slighter, but otherwise blends in well with the rest of the Vicky Neko.
When an NH-27, she could change how she appeared to some degree. A typical change involved her turning her lips a vibrant purple, as well as her tongue and eyes.
Nagase sometimes speaks with a sing-song voice that often carries sarcastic or condescending tones. She uses the phrase “wouldn't you say?” at various points in a sentence to sound cordial or deferring, but is not. She rarely is seen angry or upset, most often wearing a cool smirk instead.
She rarely carries a weapon.
Nagase wore the standard Black Spiral Warrior Dress, Type 32 uniform, but does not wear the armored jacket. Currently she dons a two-tone charcoal and black field colored Star Army Field Uniform, Type 37 and heavy treaded boots.
Nagase was created for service in the GSA's intelligence agency some time between YE 15 and YE 18. Only Nagase knows for sure, but since that time she has served as what now is known as an Intelligence Operative. She is one of SAINT's oldest operatives still in service with the organization, despite it changing names.
Nagase was given some training by the legendary Ketsurui Kikyo before that member of the venerated family entered the private sector. Nagase also received training from Kessaku Irim in the form of leadership training.
Nagase was not a founding, or even initial, member of Black Spiral. She came to the organization in YE 27, after it was established by Irim. Established members eventually fell away — some were swayed by Eve to form the splinter cell Black Spiral; others, including elite operative Tenshi Hotaru, entered civilian life. Nagase, feeling passionately about Nekovalkyrja supremacy, sided with Eve.
In YE 28, she teamed with Pumpkin to help capture Taisa Ketsurui Hanako and then-NH-22M Kotori in order to extract information out of them, as well as foil Yui's pursuit of the splinter cell through the YSS Sakura and her sister ship, the YSS Chrysanthemum. She did not meet Kotori during the interrogation; instead, a disguised Eve offered Kotori a position in Eve's Black Spiral. Kotori refused. The interrogation did not go very well for either Star Army member, though eventually they escaped — an immense failure on Nagase's part.
Shortly after that failure, Eve took what assets she had of Black Spiral's and formed her own group, The Daughters of Eve. That left many of the formerly traitorous Black Spiral Neko out in the cold. Nagase was one of several who returned to Yamatai, at Hanako's prodding, only if she agreed to divulge all information she had about the splinter cell and its new iteration.
Nagase did not know much, as Eve kept most information to herself, but was happy to give up what she could. She believed Eve had betrayed her and lost sight of the true mission.
Nagase played the simpering, remorseful turncoat rather well, saying she intended to betray Eve when it was safe, and that she made sure Hanako and Kotori did not die. It was not enough to fully convince Irim and SAINT, but she was folded back into the reformed Black Spiral with deeply limited assets in order to continue its original mission — promote friendly Neko-Mishhu relations in order to bring the SMX back to Yamatai.
Nagase did that. Her most friendly relation was with Pumpkin, whom she kept in touch with in order to obtain more information on the legendary True Lands of the True Nekovalkyrja Empire.
However, there were problems. First, her rejoining Black Spiral meant she was under the command of a subset of the group that had remained loyal to Yamatai when Black Spiral split, the Tachibana Clan. Next, she was not given many soldiers and operatives to accomplish her goals. But most important — she was being watched.
Her response involved recruiting a protege, Paizu Buka to be her No. 2, then focusing her efforts on solidifying the loyalty of what underlings she had. An understandable mistake that command had made, though, was confusing some of Nagase's deeds for those of her co-conspirators the Daughters of Eve. With her attempts to rally members once more, the true commitment of the turncoat was no longer allowable and the organization pulled Nagase back to simpler times. Safer times.
With the teachings on leadership from Irim and the memories of Kesturui Kikyo's sly spy antics still within her digital mind, much else was erased. Her ST had been brought back to a time in early YE 27 before she was Black Spiral's leader, before she had set herself on Nekovalkyrja superiority and before she was all too friendly with Yamatai's enemy, the SMX. There was no reason for a role to be played by the quasi-lobotomized Neko supremacist anymore.
Her baseline personality in day-to-day operations was more apparent, no longer suppressed as a double agent. The organization needed for that part of her to flourish was gone, though. She found being confronted with what she had did and the probably truth that her actions had to led to the downfall of what she had wanted was difficult. The true Nekovalkyrja homeland she had been searching and striving for had in some part been furthered from any's grip by her own treachery and the fiendishness of those she had worked with.
Nevertheless, Nagase Nagako was useful to SAINT for her skills and knowledge. Her innate ability to connect with important leaders and to reason with them enough to gain their confidence made her an invaluable asset. From Black Spiral leader to handler, Nagase had needed to take two steps back in order to take one forward. Now she stands between two lives and over the chasm that separates them both.
Nagase has a simplistic approach to Neko supremacy that belies her deeply rooted feelings on the matter. She knows that, as NH-17, then -27 and -33, she could kill just about anything she wanted, and that made her superior.
Much of her philosophy on the matter can be found here.
Reusing a non-traitorous Nagase backup pulled from this GM planning board post.