"Mantis' Hymn" is a recurring song in the Metal Gear series, and is the main theme of FOXHOUND member Psycho Mantis (and in the case of Metal Gear Solid 4: Guns of the Patriots, Screaming Mantis). It is a dark, somewhat repetitive song with chorus hums, meant to emphasize the ominous presence of the FOXHOUND psychic, Psycho Mantis. Although the song is thought to be mainly used out-of-universe, it was given two acknowledgements in-universe, when Naomi Hunter asks Solid Snake whether he hears the song and when Naomi reveals that Meryl Silverburgh is being controlled by Psycho Mantis due to the song being his mind control music.