When she was young, Lenalee’s parents were killed, causing her to see the world very differently. Lenalee went insane when she was separated from her brother, Komui Lee, as she is forced to become an exorcist for having the ability to use Innocence. Her sanity was only restored when Komui became the Chinese Supervisor of the Black Order.
She makes a very cute Lenalee. I haven’t seen this anime yet, but it seems pretty popular with all the cosplays going around. I think I’ll put this on my to-watch list.