This is the signature tune to the original Ghost in the Shell movie, 謡Ⅲ～REINCARNATION / Utai III Reincarnation, by the esteemed anime composer Kenji Kawai, and hauntingly styled on a Noh chant; however, it has here been given a rather interesting Vocaloid workover, with singing provided by Meiko and Ren.
Nico. This is a .swf, hence the lack of play controls.
The reworking is a commemoration of the release of 2.0.
See also the various vocaloid reworkings of the “Sea of Miracles” Lodoss War signature tune for a similar sort of effort.