Lenalee is Komuis younger sister and an Exorcist in the Black Order. Her parents were killed by an Akuma when she was young, leaving her with only one family member, Komui. Because she is an Accommodator, the Black Order took her away from him to Headquarters against her will. For three years, Lenalee felt like a prisoner at Headquarters and attempted suicide, leading to her being restrained and tied to her bed. However, after Komui joined the Black Order, she became more comfortable in her surroundings.
Lenalees "world" consists of her friends and family; if something terrible happened to them, she would be devastated. Her anti-Akuma weapon is a pair of boots called "Dark Boots," which increase speed and strength greatly in the legs when invoked. Lenalee can also fly with these boots.
After the battle against the Level 3 Akuma, Lenalee lost the ability to use her Dark Boots for a period of time. However, it has been suggested that her innocence may be the heart of her abilities as an Exorcist.
In chapter 153 she made a promise with her innocence so it would become stronger to protect everything she loves, and so it liquified and fused with her blood, creating a better version of her Dark Boots. After defeating the Level 4 Akuma, the boots transformed into a red ring that stays on her legs until the innocence is activated.She is the first known exorcist to create this new type of innocence named "Crystal Type."