"Night Walker" is Hayakawa-P's first work featuring Kagamine Len (append power) using the V3 editor.
Hayakawa-P mentioned on his video description that the video contains rather "grotesque" contents as a warning to those who aren't comfortable with such. He also commented how it was more or less a "zombie Halloween" song.
"Night Walker" tells a story of Len waking up, realizing he is a "zombie". He first questions who he was, as he can't feel anything, and is confused. Later he regains some memories regarding Rin (she was "blurry" at first) who could be interpreted as the person who killed Len in the first place. Nonetheless, Len speaks of how he loves her, and he decides to meet Rin again.
A small bit of trivia concerning this VOCAROCK song is that the eyes shown in the beginning of the video are those of Hayakawa-P himself (and are credited as such).