Ryuki Kashin

Ryuki Kashin was the elder sister of Ryuhime Kashin, and took care of Levi and Ryuhime during their younger days. She disappeared after a battle with Levi, with her whereabouts being unknown until after a possessed Ryuhime got defeated by Levi, and she stabs her abdomen from behind with the Mystical Weapon Murasame.

Personality
In front of a younger Levi and Ryuhime, she appears to be the kind and caring older sister to them. However, it was all a cover to obtain more power, going as far as massacring an entire village in order to resurrect them as her pawns, as well as killing and absorbing Malebranche's Dragnasuo in order to consume its power.

Appearances
Ryuki is a slender and quite developed woman(?) with long blonde hair that does not contain any ornaments. In Combat mode, her attire consists of a kimono that exposes most of her navel and cleavage as well as a long skirt.

Under the possession of Murasame, she grows a horn from her left forehead, as well as scales on her left cheek and shoulder. Her eye color is red, although it is unknown if that is her original eye color. Her attire doesn't change much, aside that her kimono now covers her navel.

Abilities
Ryuki was supposed to be dead from the start of the series, and when she reappeared, she was mostly using the abilities obtained from Dragunazo and Murasame. As such, it is unclear what capabilities she is able to use.

Weapons
Famed Sword Monohoshizao

In the battle against Levi before her disappearance, Ryuki wielded this sword against her. Levi forsaw the sword's "death", which led to the sword's tip begin cut by Levi. However, Ryuki managed to use the broken tip to stab Levi's covered left eye, believing it to be the "Evil Eye" in the final moments before her disappearance.

It was with this sword that she used to massacre the people of her village.

Mystical Armament Murasame

After Ryuhime sealed her control over Dragnasuo's power with her control over the souls that Ryuki consumed, she used Murasame as a last resort against Lugh and Levi.