Akutagawa Ryunosuke’s “Two Letters” is a short story published in the second volume of the magazine “Kokucho” in September 1917. “Two letters” describes the main character Sasaki, who claims his wife’s affair to be a “doppelgänger phenomenon”. It is for this reason that Sasaki is considered to be a “madman”. Sasaki identifies his wife’s hysteria as the cause of the doppelgänger’s manifestation, which suggests that adultery may occur. Much of the previous research on “Two Letters” is centered on the insanity of Sasaki and the doppelgänger phenomenon, which is used to represent Sasaki’s madness. I intend to analyze the work overall and attempt a new interpretation.