Ikaruga is a member of the Trinity Raven, a group commanded by Jellal from Death's Head Caucus. Her appearance is roughly that of a geisha though her power are more in line with that of a samurai. Ikaruga is able to cut practically everything. Besides, she likes to create a dramatic atmosphre using the poetic manner of speech.
[Spoiler] She confronted Shou as he tried to escape from the Tower of Paradise with Erza (who was in card form at the moment) and attacked them out of nowhere. Luckily her attacks distorted the power around the card holding Erza, allowing Erza to escape and confront Ikaruga. Erza used all type of her armors against her but each was cut to pieces by Ikaruga's blade. Eventually Erza was only down to a pair of pants around her waist and cloth around her upper body. Ikaruga thought of it as an easy win, and the two attacked one another. However much to her surprise Erza was able to deal a mortal blow and defeats her.
While their fates were not shown in the manga. In the anime its revealed she and other members of Trinity Raven managed to fly away from Tower of Heaven. [/Spoiler]
