Kirito is the main character from Sword Art Online. While he is undoubtedly a male for most of the series, during the Phantom Bullet Arc Kirito is given an avatar with a feminine appearance after joining Gun Gale Online.
While in Gun Gale Online, Kirito has long black hair and black eyes. His clothing usually is either a white shirt with black pants or black shirt and pants along with a breast plate.
Kirito will sometimes use the fact that most players mistake him for a girl in order to mess with some of the male players such as cheering "Cheer for me!" while striking a cute pose leaving them completely oblivious to the fact that he's actually a boy.