Emerald Sustrai:
A being from the realm of Ramment. Upon arriving at Azur Lane, Emerald became a quick friend of Josh Erwin: the commander of Azur Lane who took her under his wing and trained her as a best commander like him.
Looks:
(Without Armour)
Armour:
(Imagine that her Armour is reinforced and dark green colour)
Command spells:
Josh Erwin: the main commander of Azur Lane, married to Hood (in the Mandalorian of Azur Lane story). Josh took his friend: Emerald under his wing to be trained. He treats her like a sister thus allowing her to have a Secretary herself.
Looks like
Armour:
Command spells:
As for their weapons: find out in the story.
(Note: I don't own the pictures. Please don't sue.)