Not blue.

Background
"not blue." was first uploaded on March 17th 2009. It's Shokkidana no Hito's most notable work using Kagamine Len. It reached over 16,000 views, however, due to Shokkidana no Hito's retirement (resulting her to delete her mylist, and account) not blue. was removed from Nico Nico Douga.

Originally Shokkidana no hito made a self cover with her being the vocals, however it was removed as well. Nico kara and utaite covers or other derivatives are still made despite Shokkidana no hito's retirement.

The piano ballad tells a story of Len, who have been friends with someone since childhood. Unfortunately for him by the end of the song, that person whom he was so close with left / died; interpretations are widely open for this song.