Aoiro Rinne

Aoiro Rinne is the eight Noble Art of Shizuku Kurogane.

Description
Aoiro Rinne is the strongest Noble Art of Shizuku Kurogane, in which she devised soon after her defeat at the hands of Rakiri, Touka Toudou in the Hagun Selection Battles after she realizes she the reasons for her defeat was because of Shizuku having human flesh. Through the use of her water-based abilities and healing technique, where she manipulates the trillions of cells inside her to transform herself into water.

As such Aoiro Rinne can be used to repair the damages which Shizuku received even prior to the Noble Art's activation even after she was bifurcated by Wallenstein's Bergschneiden in a desperate attempt to rescue Nagi from his former teacher from Rebellion. Aside from being able to heal from injuries, Shizuku is able to manipulate the air around her letting her suffocate or even drown her opponents even on land, as well as cause ice spikes to erupt from their bodies.

After the Seven Stars Sword Art Festival Finals, Shizuku later reveals that Kiriko Yakushi, a fellow water magic-user can use a similar technique as her Aoiro Rinne without the exact same weaknesses as hers. She had also trained under Kiriko to learn the healing techniques of the famed doctor.

Aoiro Sekai
In the Vermillion Empire Arc, Shizuku, after Ikki has died at the hands of Or-Gaule, revealed a more improved version of Aoiro Rinne named Aoiro Sekai (青色世界, Blue World), which can be used on others as she could revive Ikki from the death. As she uses this technique, she manifests a pair of wings made of her magical power, then the feathers of her wings break down a person's body into single-cell units when they touch and rebuild the body. She could also use her own somatic cells to assist Ikki due to being siblings.

Weakness
Despite being powerful Aoiro Rinne is extremely dangerous requiring immense precision and concentration as a single mistake will kill her when reforming herself. Even Shizuku herself who has superior magic control resulted in her body being distorted after being used for the first time and required painful surgery from Kiriko Yakushi.