Fate Crossover Drama CD: Butterfly Effect (FateクロスオーバードラマＣＤ『バタフライ・エフェクト』?) is a drama CD included in the TYPE-MOON Ace Volume 10 magazine in July 1, 2015. It was written by Eiichirou Mashin.
Story
Nero Claudius is summoned by Medea instead of Assassin in the Holy Grail War in Fuyuki, they fight against Rin Tohsaka and her servant Passionlip. Archer is summoned by Rani VIII in SE.RA.PH and she prohibits him for using underwear.