The commanding officer of Combined Fleet Base Azur, short Azur Base.
Location: Azur Angel timeline
Role: The voice of reason in a world of chaos, Commander Daeh is the crank that keeps the warmachine against the Siren invaders turning. Stemming from the homeland of Iron Blood, his military doctrine focuses on cunning and strength in equal measure.

The XO of Azur Base and self-proclaimed friend to all Kansen.
Location: Azur Angel timeline
Role: A Former investigative journalist turned second-in-command of Azur Base, Lt. Angel is a chipper, optimistic and polite woman. She had made herself a name in wartime journalism and investigative journalism, uncovering several worldshattering plots. Her bravery in her line of duty earned her a role with the Admiralty, ultimately leading her towards her current post at Azur Base. She decided to strictly go by her pen-name to protect her loved ones.

A Sakura Empire battleship stemming from a fallen timeline. Taken by the Sirens before the doom of her world.
Location: Azur Angel timeline
Role: Ashitaka serves as a main character to the story and as the main motivator for her mate Okita.

A Sakura Empire Battlecruiser, coming from the same timeline as Ashitaka does.
Location: Various, over the course of the story.
Role: The de-facto main character of the story, this Kansen’s goal is to be reunited with her mate and she will stop at nothing to achieve this.

A Siren Tester that has been washed into the Azur Angel timeline.
Location: Various, mainly Azur Angel timeline.
Role: Through Nemo’s eyes, the reader is introduced to more knowledge about Sirens. She assists the cast against her kin.

Eternity is an AI assistance program, developed by the Sirens. Once a Siren has proven herself worthy of it, she will receive a copy to accompany her from then on.
Location: Various. Many Sirens carry a copy but these are all distinct entities from one another. With one exception, Nemo’s copy, they are all linked via the AI Mainframe.
Role: Support, character building and source for lore at first, Nemo’s Eternity copy has grown into a character of her own.

The leader of Expeditionary Fleet 01, this mysterious entity reigns with absolute power.
Location: The Median Dimension / The Space Between
Role: The ruler of the Expeditionary Siren fleet that is engaging with humanity, she is acting as the story’s primary antagonist

Part of Siren Expeditionary Fleet 01, this Siren focuses on a non-combatant role.
Location: The Median Dimension / The Space Between
Role: Her role within the Siren fleet is a supportive one. She is the master of the Eternal Engine, a factory Siren that is responsible for building and maintaining the Siren forces for their engagement on Sol 3.

Purifier is an Eradicator Siren of Expeditionary Fleet 01 and a vital part in the post-experimental cleanup.
Location: The Median Dimension / The Space Between
Role: As her role frequently brings her into contact with the different timelines, she acts as secondary antagonist on the frontlines.

Head of the Observer Corps of Siren Expeditionary Fleet 01
Location: The Median Dimension / The Space Between
Role: As is her duty, Observer oversees the data gained during Siren experimentation and heads multiple projects, aimed at generating more data. As such, she is acting as secondary antagonist in the shadows.

Part of EF-01s Eradicator Corps and younger sister to Purifier
Location: The Median Dimension / The Space Between
Role: Similar to her sister, she acts as antagonist in direct conflict with the timelines. She is however less experienced, thus posing less of a threat, if there ever could be such a thing with Sirens.

A member of the Siren War Fleet specialized on eradicating entire star systems
Location: The Median Dimension / The Space Between
Role: One of the mightiest Sirens in terms of raw firepower, she acts as antagonist to both humanity and even her fellow Sirens.

Youngest of the mighty Yamato battleships, the serene kitsune is a link between worlds.
Location: Most, if not every, version of Sol 3 that the Sirens interacted with has a Shinano.
Role: Shinano is unique, as she is the only Kansen capable of accessing a key aspect of the world, linking her to every other version of herself throughout the different timelines. She not only supports the cast but also represents an important aspect of the story.