Izumi Nase

Izumi Nase (名瀬 泉 Nase Izumi) is one of the secondary characters of the Kyoukai no Kanata series. She is the head of the Nase Clan as well as the older sister of Mitsuki and Hiroomi Nase.

Appearance
Izumi is a very beautiful young woman with neck-length black hair that is seen let down while it hangs on the right side and purple eyes.

She is usually seen wearing two necklaces, one that has a small fish and the other with red and green jewels. Izumi has a little beauty mark below her mouth slightly to the left. So far, she has only been seen wearing shorts: a plaid pair and the other straight black in color; also wearing long-sleeved shirts. She also wears a bracelet on her right wrist. She is noted to be a beautiful young woman.

Her appearance gives off a motherly aura.

Personality
Befitting the face of the Nase family, Izumi exudes a level of elegance befitting of someone in her position, although this is contrasted by her tendency to be frank towards people whilst retaining her kind expression.

History
With the notable absence of parents in the Nase household, Izumi acted like a mentor for her younger siblings, teaching Mitsuki and Hiroomi the ways of the Spirit World Warriors.

Although her "lessons" seem harsh, imprinting her younger sister with the idea that sacrifices need to made for the sake of their duties, Mitsuki's life under Izumi's care ultimately shapes her into how she is now.

Story (Anime Series)
Izumi is introduced as the representative of the Nase family, often at times speaking on behalf of the family and performing duties such as overseeing the Spirit World Warriors who inhabit the surrounding neighborhood of Nagatsuki City.

During the appearance of the Hollow Shadow, Izumi is visited by Miroku Fujima, a member of the Spirit World Warrior Society, and permits him to observe the behavior of the Hollow Shadow. She later assumes a more active role during the powerful Youmu's advance through the neighborhood, erecting Glaciate Barriers to protect the town from the fireballs Akihito Kanbara created whilst in his Youmu form.

In the aftermath of the Hollow Shadow's defeat, Izumi retrieves its Youmu stone and presents it to a mysterious person, saying: "To stall the Spirit World Warrior Society".

The day after the Hollow Shadow incident, Izumi suspends Mirai Kuriyama's Spirit World Warrior license for a month for disobeying orders and reprimands Akihito for his unnecessary involvement in the Hollow Shadow incident.

Mirai's license as Spirit World Warrior was reinstated during the time where Izumi discovers the manifestation of the Calm, which she later links to the powerful Youmu called "Beyond the Boundary".

Amidst an ongoing power struggle between the Spirit World Warriors Society and the Nase Clan, Izumi decides to deal with Beyond the Boundary to prevent the balance of power from tipping in favor of the Society. In a short encounter with the Half-Youmu, she forces the Youmu inside Akihito Kanbara, which is a portion of Beyond the Boundary, to manifest.

Afterwards, she asks for help from Mirai Kuriyama, her long-time accomplice in attempting to kill Akihito, while she faces Miroku Fujima as an enemy for the first time.

However, though Izumi's initial plan of eliminating Akihito failed due to Mirai's display of sympathy towards him, Izumi manages to persuade Mirai into sacrificing her life to extract Beyond the Boundary from his body.

Several months after the attack on Akihito, Izumi appears to the former Half-Youmu to explain what happened, especially about Beyond the Boundary and Mirai's decision of self-sacrifice.

However, unlike her first assumption, Mirai managed to survive after absorbing Beyond the Boundary into herself. Only Miroku Fujima (who later forces the massive Youmu into an unstable state) and Akihito's mother, Yayoi, know of this information.

With Miroku once more attempting to make chaos in Nagatsuki City, Izumi is forced to abandon her plans to interrogate Yayoi in favor of stopping Miroku.

Although Izumi was able to apprehend Miroku with aid from her siblings as well as help from Miroku's former accomplice, Sakura Inami, she ends up falling into one of Miroku's traps. Here, he not only exposes Izumi's true nature as a human with a Youmu inside but also does so in front of Hiroomi.

After her true nature is revealed, Izumi decides to vanish to parts unknown, leaving the responsibilities of the Nase Clan to Hiroomi.

Three years before
In the past, Izumi left the clan for some time but returned to continue guiding Mitsuki and Hiroomi, tasking the latter with capturing and/or eliminating the Half-Youmu, Akihito Kanbara.

However, though she trusted her brother's capabilities, Izumi decided to intervene after finding out Miroku Fujima (then an unaffiliated Spirit World Warrior) was also interested in capturing Akihito.

After fighting each other to a standstill, Miroku retreats, but not until assuring Izumi that they will cross paths once again.

Eventually, with some information Mitsuki acquired by coincidence, Izumi learned of the cursed blood of a particular Spirit World Warrior family that had the potential to suppress Akihito's Youmu side.

This lead Izumi to begin the long process of tracking down the survivors of this nearly extinct clan and eventually discovering the whereabouts of the only living member: a young girl named "Mirai Kuriyama".

Story (Mirai-Hen)
Izumi is a secondary character in the movie, unknown at first, but soon revealed to be one of the hooded figures threatening both the Spirit World Warriors and Mirai Kuriyama.

She now donned in a black bodysuit and still wielding her trademark double-edged interlocking naginata, the Youmu inside of Izumi's body has more or less taken her over completely, although she is able to have brief moments of clarity.

Throughout the movie, Izumi fights both Hiroomi Nase and Akihito Kanbara whilst also questioning Mirai Kuriyama if she wishes to know more about her past.

It's then revealed that she took on the Youmu from Miroku Fujima in order to protect both her family and everyone important to her.

At the climax of the film, Izumi is able to beat the darkness with the help of Hiroomi Nase and in the credits it's shown recovering from the ordeal, however it's unknown if she's retaken her position as head of the Nase from Hiroomi or not.

Glaciate Barriers
Even among the elite Nase Clan, Izumi stands out as an exceptionally skilled Spirit World Warrior, one of the few individuals who're capable of making use of the Glaciate Barriers.

In fact, her skills with the technique are great enough that she's able to encase (or more accurately "sink") her target's consciousness into a dormant state, such as when she made her secretary fall into a limbo-like state or how she was able to suppressed Akihito's human-side.

Along with her abilities as a Spirit World Warrior, she's a master of the naginata and is easily capable of dual wielding.

Weapons
Izumi's primary weapon is a double-bladed double-edged naginata that is capable of separating into a three section staff linked by chain.

Etymology

 * The name Izumi means "fountain, spring" (泉).
 * Izumi's surname Nase means "name, noted, distinguished, reputation" (名) (na) and "swift current, rapids" (瀬) (se).
 * Nase may be aptly interpreted as "renowned position", considering that the Nase family is a prestigious family among Spirit World Warriors.

Trivia

 * Izumi has a picture of water serpent-like Youmu in the main room which is actually a Youmu in Glaciate Barriers