This movie is a film adaptation of a short story Junji Ito wrote called Tomio: Red Turtleneck. This short story was published as the third chapter of his anthology called Fragments of Horror. Curiously, the movie was released in 2011 while the horror anthology novel wasn't released until 2013.
This is Junji Ito's only foray into film directing, despite the fact that many of his written works have been adapted by countless other directors.