Ymir's Ocean Girl

The Ymir's Ocean Girl is an unnamed girl, introduced in Toaru Majutsu no Index SS: Kanzaki.

Appearance
The girl has blonde hair, blue eyes and white skin, with a tan around the time she met Kanzaki. She wears a short dress with a crest embroidered near the hem of the skirt.

Background
The girl came to Uphill Island to research the impacts of Christianity on other religions. As she didn't expect anyone else to come, she neglected using people-clearing magic and used her magic to control the water currents to prevent the sea from eroding the rock. This led to her being seen controlling the water, resulting in the precarious balance between Uphill Island and the surrounding islands being skewed. Fearing that the locals might be slaughtered if she left, the girl remained on the island.

Toaru Majutsu no Index SS: Kanzaki
Due to receiving information that someone was preparing a spiritual item capable of large scale destruction, Necessarius dispatched Kanzaki Kaori to the island, together with the Jeans Shop Owner and the Tour Guide. When Kanzaki found the girl, she was crouched atop a black rock, doing some kind of work. The girl asked who she was, however after Kanzaki voiced her intent to deal with her if she was hostile, the girl asked her to come over to the rock.

After checking for a trap, Kanzaki jumped over to the rock and the girl showed her a set of non-magical Norse runes, left behind by believers of Norse mythology around the time that Christianity was being forced on others during the Age of Exploration in hopes of keeping their way alive. She then explained how she was investigating the effects Christianity had on other cultures during that time.

Believing that the girl wasn't the threat she was after, Kanzaki gave the girl a charm which was both a tracking and communication device, to be used either for an alibi or to contact her in case of an emergency. After Kanzaki mentioned how it would be easier to search if she knew what kind of spiritual item it was, the girl suggested that it perhaps had something to do with the ocean, mentioning how there were stories of great floods similar to Noah's Ark in many religions around the world, including there. She went onto to say that it is related to why Uphill Island was hated by the people of the surrounding islands - as it rose from the sea, the other islands suffered due to the other effects of the change in the Earth's crust, which is why the people there caused the people of the island to suffer and why some might use a flood to wash the others away.

As Kanzaki went to leave, telling her to try not to run into her enemy alone, the girl said she was staying put. When Kanzaki warned her about the risk about remaining there, the girl replied that it wasn't as dangerous as she thought, since she could create a flood by herself. Immediately afterwards, a red flood consumed a third of island, sweeping Kanzaki out to sea and smashing the runes but avoiding the girl.

Using the communication device, the girl described how the world was created in Norse mythology from the corpse of Ymir and the flood of blood from his corpse which drowned the giants. As her hands started to turn purple, the girl mentioned the spell's name, Ymir's Ocean, and again brought up the fact that stories similar to that of Noah's Ark were present in religions across the world. The wire the charm was on then contracted, but the girl put her hands between it and her neck. After being cut, she tore off the wire and prepared to throw the device away, saying that Kanzaki had bad luck to meet her on the sea.

However she then heard Kanzaki saying she wasn't given a life normal enough to call that bad luck and spotted her three kilometres out to sea on skiis. Kanzaki described Ullr, categorized by some as a god of skiing and one of the Aesir who weren't drowned in the flood, meaning that a spell based on Ymir's blood wouldn't drown her while on skiis. She then asked the girl if she was trying to save the people of the island, seeing persecution like in the age she researched. The girl described her carelessness and how she had unwittingly affected the balance between the islands, such that the people of Uphill Island were in danger of being killed by the inhabitants of the surrounding islands.

Though understanding that the girl's actions might be necessary, Kanzaki didn't approve of her using the spell against the normal people of the islands. She then sped towards the girl on a wave, intending to defeat her in a single blow. The girl used salt pillars to attack her, telling her not to underestimate Ymir's Ocean, but Kanzaki evaded them, replying that she shouldn't underestimate a Saint. In desperation, the girl created a huge wave but Kanzaki used it to reach her and knocked her out.

When the girl regained consciousness, Kanzaki told her how attacking the surrounding islands would be the wrong course of action. The girl replied that she knew that, but there were people who didn't and they wouldn't listen to her. Kanzaki asked her what she would do next, if she would leave the island with them. The girl declined as she had to try to resolve the misunderstanding and restore the balance between the islands in order to save the residents of Uphill Island, with words rather than violence. At that moment, a large noise reached them - an unpleasant cheer from the island's residents who had witnessed the flood, believing it to have come to sweep their enemies away. The girl then asked Kanzaki if she understood - that was why she had to fight.

In the end, the girl remained on the island as Kanzaki's group left to try and persuade the people of the islands, hopefully without Ymir's Ocean.

Abilities
The girl uses a spell called Ymir's Ocean (赤き洪水 (ユミルズオーシャン)) which allows her to control water and salt in the ocean. In order to use it she needs to change the salt concentration in her blood to match the ocean's, as the oceans were created from Ymir's blood in Norse mythology. Since this would damage her organs, she concentrates the salty blood to her hands and prevents it from flowing to the rest of her body. As this means restricting her blood flow, she can't use Ymir's Ocean for long durations.