Honoka

was a kunoichi working with the researchers on a remote island.

Background
While researchers worked on the Ultimate Summoning Animal, Honoka was assigned to restrain the beast using her sealing techniques. However, at some point in time the beast got too powerful for her technique to restrain it and killed everyone.

Appearance
Honoka had dark eyes and long red hair in which she wore a white band. She wore a purple, sleeveless kimono blouse with yellow trimmings held close by a traditional obi with a long, streaming bow tied to it, mesh armour underneath it and a short white skirt. She seemed to prefer going barefoot. She bears a strong resemblance to Kushina, Naruto's mother, which hints at blood relations.

Adventures at Sea Arc
With her soul unable to find rest, she roamed the island as a spirit waiting for an opportunity to fulfil her duty.

As the Konoha shinobi came to the island to save Guy, Aoba saw her and chases her until she shows him her research. Later, she also shows him the Ultimate Summoning Animal before it was awaken.

Trivia

 * Given her red hair, skill in sealing techniques, and the history of the Uzumaki clan, Honoka was suspected to be a member. A book in an old abandoned house on the island even mentions finding a survivor of a certain clan of ninja.