- "There is always a path through the darkness in the direction you desire, I'm sure."
- — Subaru —
Depth is the sixteenth episode of .hack//SIGN.
In the real world, the comatose girl that is supposedly Tsukasa is shown with her vital signs dropping to zero. Mimiru wonders if Tsukasa, who can feel pain in the game, will die if he dies in the game. Bear tells her not to worry, as the real life Tsukasa is apparently okay. He tells Mimiru that they can do nothing but wait for Tsukasa to reappear.
Crim reports to Subaru about what happened at the upside down castle, stating that the Key of the Twilight was not there. He also says that both he and BT had to do a hard reboot in order to re-enter the game after the area collapsed.
Tsukasa is soon brought back from death in The World and appears at the bedside of the sleeping girl. The voice welcomes him back, saying the same words she said before: that she is Tsukasa's ally and that they should stay together, away from the outside world. Tsukasa disagrees and wonders why he exists in The World.
Subaru appears in Mac Anu to tell Silver Knight not to worry about her and to handle most of the matters relating to the Crimson Knights. She then checks a field where she meets Tsukasa. Tsukasa does not like the fact that he is trapped and that, even if he dies, he is resurrected in The World. He feels that since he cannot escape, he isn't truly alive. Subaru tells him he is indeed alive, and that she will be waiting for Tsukasa if he were to one day return to the real world. She also reassures him that he will eventually find the path he desires.
Bear meets with BT to discuss where to go from here. There are three clues that may aid in finding the Key of the Twilight, and they are all centered on the old man they met at the upside down castle. Bear soon receives an e-mail from Mimiru and goes to Dun Loireag to meet with her and Subaru. Subaru tells him about her encounter with Tsukasa earlier and is worried that Tsukasa may lose his self-awareness if he continues to encounter hardships such as the one in which he died.
Mimiru receives an e-mail from Tsukasa saying that he can meet with them, so she takes Bear to go to him. Tsukasa seems to have no memory of the time he found out what the Key of the Twilight was, but Bear stops Mimiru from pressing the issue. Tsukasa, bothered that he can't remember something so important, returns to his hidden area and falls asleep by the side of the sleeping girl.
This is the only episode in which Aura is actually touching her bed.