Asami Shimoda is the voice provider for Kagamine Rin & Len. She covered the songs Clockwork Lullaby and South North Story on her album Prism, and covered the songs The Daughter of Evil, The Servant of Evil, Twiright Prank, and Regret Message; her cover of Twiright Prank was the first one to be released.
daishi mastered the original versions of Chrono Story and Judgment of Corruption.
Hiyama Kiyoteru provided vocals for Project "Ma" and Clockworker - Recollective Musicbox -.
Jounetsu-P, also known as Tetoteto (てとてとtetoteto), has released various unofficial covers of mothy's songs. He composed Red Shoe Parade and co-composed The Flames of Yellow Phosphorus with mothy.
Kaai Yuki provided vocals for Handbeat Clocktower.
Kangaroo Suzuki composed the instrumentals featured on The Daughter of Evil ~Gemini of Charm~ Vocal and Soundtrack.
Lily provided vocals for "Ma" Survival - Who Will Survive? -.
Mitsuyasu Yanagita provided the guitar for Seven Crimes and Punishments.
MAYU provided vocals for Bloodstained Switch and Neomaria of the Inverted Gravestone.
mothy is presumed to create all of his officially released music unless otherwise stated.
Nekomura Iroha provided vocals for "Ma" Survival - Who Will Survive? - and The Song I Heard Somewhere.
SF-A2 codename miki provided vocals for "Ma" Survival - Who Will Survive? -.
Saori Hayami sang the version of Fictional Masquerade that was featured in Engage Princess.
Signal-P, also known as Dios, helped mothy produce and sell the albums EVILS THEATER, Screws, Gears, and Pride, and EVILS FOREST. He then mastered the original versions of Fifth Pierrot and The Steel Lady, Rilia-Renée.
Soraru sang Half Blood for HalfBlood: Love Trembling at the Boundary.
Travolta-P arranged the songs The Daughter of Evil (arrange version) and The Servant of Evil (arrange version) featured on The Daughter of Evil: BGM Reading Collection.
uniMemo-P collaborated with mothy under the name Akuyurin (あくゆりんakuyurin); he tuned "South Rin", arranged, and wrote the English lyrics for South North Story and tuned BMD2R, arranged, and provided guitar for Screws, Gears, and Pride. He released the album Screws, Gears, and Pride with mothy under the Akuyurin alias.
VY1 provided vocals for Torture Tower Doesn't Sleep.