Sigh

Background
The song was first uploaded on January 4th 2012 as one of the tracks featured in the compilation Kagamination. Unlike Hayakawa-P's Swaying World, Love, and the Future or Live-P's The Worst Carnival which were uploaded the day the compilation was uploaded, iroha(sasaki) uploaded the song "sigh" half a year after the compilation was first distributed on VOC@LOID M@STER.

Like the booklet illustrated by Suzunosuke, the PV is also done by the same person. It's also said that the version uploaded to Nico Nico Douga is remastered from the one used on the compilation.