Tsukasa is a Wavemaster and the main character. He is a young silver-haired boy clad in grey robes, At the start of the series, he is seen waking up to find himself in a dungeon in The World, but he has no idea why he is there or who he is. Not much time passes until Tsukasa discovers he is trapped in the game, unable to log out, while his real body is in a coma. He is initially depicted as a cynical loner who tends to avoid others as much as possible, but at the story progresses he begins to warm up to Mimiru, Bear, Subaru, and others.
In the real world, his name is An Shouji, and he happens to be a girl. She was raised by her father after the death of her mother, and was physically and mentally abused by him. His abusive behavior also distanced her from her gender: he treated her like a boy, refusing to allow her to use feminine products and basic hygiene products. There are also subtle hints that her father is an alcoholic. After awaking from her coma, Ryo Sakuma, the player behind Bear, becomes her legal guardian and allows her to go to a boarding school. She meets with Mariko, Subaru's player.