On This Perfect Day is the debut album by Dutch singer and musician Arjen Anthony Lucassen's side project Guilt Machine, released in August 2009.

The cover of the album was made by Christophe Dessaigne, an artist discovered by Lucassen on Flickr.

The music deals with "the destructive psychology of guilt, regret and the darkest form of secret -- the secrets we hide from ourselves",[2] and the music ranges "from dark and heavy to atmospheric and melancholic",[2] as can be noticed via the preview track published at the band's MySpace page.

Elements that were praised included Steverlinck's voice and the dark atmosphere developed by Lucassen; Metal Storm considers it "the darkest and most melancholic [album] the Dutchman has ever released".

[4] However, Sea of Tranquillity stated, "I'm sure there are going to be plenty of Ayreon fans who might balk at the overabundance of atmospheric and mellow moments here and miss the more upbeat and bombastic elements of Lucassen's other releases".