Mai listens for the tone.

"That tone... what is that tone?"
Mai Minase

A in C major (ラ音) is a musical note that is heard when players are temporarily drawn into The World or The World R:2, often coinciding with the appearance of an AI or other abnormality unrelated to normal gameplay. The tone usually goes unnoticed by those who hear it, though Mai Minase, an experienced musician, was able to identify it and, once conscious of it, avoided its effects, which seem to subliminally distract the player and blur the line between reality and The World.


  • Though the term "A in C major" is used in the series to refer to this particular pitch, it is one that is not typically used, as it fails to refer to either its frequency (440 vibrations per second) or its placement in the musical scale (the fifth octave). Common ways to refer to the pitch are Middle A, Concert A, or A440.
  • The note was first used in In the Case of Mai Minase of .hack//Liminality when Mai Minase and Tomonari Kasumi are attacked by Skeith.