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.

Abilities
The girl uses a spell called Ymir's Ocean 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.