Eirin

Eirin is a member of BlueBird having the power to create crystals. With her crystals she is able to create animated animals, often blue butterflies which allow her to watch through them like a spy camera. She often uses a sword when it comes to one on one battle. However, the strength of her crystals depends on her emotions and intent. They are only temporary and take time if they are to be permanent.

When it comes to fighting, she shows herself to be near unbeatable as she does not like to show her weakness. She will not tell what it is, even if her opponent accidentally comes across it. Most of her crystals are made from aquamarine as the less strong it is the easier it is for her to form. Making quartz or topaz takes more of her energy and she has only ever made one or two permanent diamonds in her lifetime.

Often when she sees Takehiko, they engage in battle which they consider to be a 'small banter' but is easily mistaken for a serious and overheated one by onlookers.

Appearance
Eirin is a girl with pale skin, blue-green hair which she often ties into a pony-tail, leaving a fringe. To match, her eyes area deep sea green colour. When not in her Blue Bird uniform, her favorite outfit is her blue dress, cape and crystal shoes. When wearing other clothing she tends to remain rather stylish from head to toe. On her back is a fox tattoo alongside with her team crest.

Personality
She often seems to laugh at people as if she is above them in but when she actually laughs because it is amusing to her rather than at their failure. She is a relatively open person if you ask her a question directly but she will generally put on a facade. However, she often retains her need to figure things out on her own and keep questions to a minimum. She does not like to show her weaknesses but she will not hesitate to help others when necessary.

She does not like to be wet, preferring the heat and even being able to walk through fire. She also becomes excited when going to other places as she hardly travels.

Backstory
In her past, Eirin came across Yuri but she does not mention when, where or what sort of relationship they had. This is something Yuri knows little about due to her state of being a reincarnation as human and Eirin having had lived for over a hundred years despite her immortalized age being 19. It is hinted that Yuri's kindness changed Eirin from her colder past self when she would kill anyone who opposed and was of no use to her.

Eirin does not completely know her origin but through research of her own has found herself to be part fox-daemon and angel as well as human. Within her lies a crystal feather from an angel which unlocked her powers but also keeps her alive due to the instability of daemon and angel blood within her. Her daemon and angel origin allow her to have the natural ability to play the flute.

Some time after her birth it became hard for Eirin to suppress the deamonic side of her without complete concentration. Much like a kitsune which holds its power/soul in a pearl, Eirin developed a pearl which stopped her from having to take a lot of effort to maintain the balance. Without her pearl Eirin's hair and eyes turns silver and her angel wings, ears and tails appear.

During her tween years, Eirin grew up with Takehiko learning how to fight using the ancient arts under their master. However, for a yet unknown reason, their master disappeared leaving both a task to gain strength. Both eventually found sword masters on the beginning of their path to become stronger.

Before meeting Yuri, Eirin had accumulated an army which followed her every command. As she took over land, Eirin assigned citizens people to various jobs making her kingdom flourish and unintentionally, everyone happy due to her lack of requirement for grand estates, preferring to keep to a single one. However, she was betrayed and gradually rumors spread to create fear of her power. The people captured her, knocking her out before she could try anything. When she awoke, she was tied down and saw one man light the pyre beneath her. Angered, she let the ropes burn away, already fully aware of the fire's inability to burn her and turned the burning into a massacre of all the people in the vicinity who attempted to burn her. After that, she left and rebuilt her home in isolation where she forced hibernated herself. When she stepped out of her home years later she found a way to travel back to her original home world and left the one she was in forever.

Eirin has taken trips to many different worlds visiting them only once or twice but even so she considers it a small list of places. She has managed to obtain many artefacts, one which includes a key to a library which is protected from destruction. This protection is applied to all the books in there which include different prints of every book since a few hundred years before her birth

Present
Eirin is a part of the BlueBird team often conversing with Noire and Mystere due to an outside relationship she has with them. She also gave a key to her library to Elise after she lost her clinic in a fire.