Kirigaya Suguha (桐ヶ谷 直葉), or also known as Leafa in game is Kirito’s adoptive sister in the real world, although later revealed to be his cousin. She’s an accomplished kendo practitioner, having practiced for 8 years, following her grandfather’s wishes.
Leafa originally hated VRMMO games for it hid peoples’ nature and reality, as it did with Kirito. She used ALO in order to understand Kirito better when he was trapped in Sword Art Online. Leafa won the Sylph competition, earning the title as the most powerful Sylph before the events of the Fairy Dance arc.
Leafa learned how to play ALO from her classmate, Recon aka Nagata Shinichi. Leafa is becoming very good at ALO, as a result of many years she has practiced kendo and the abilities learned there were very effective for battles in ALO. She loves flying in the game very much that REcon even nicknamed her as “Speed Holic.”