This article examines the development of Akutagawa’s literature from the middle to the end of his life, based on “Shinkiro(蜃気楼)” (first published in Fujin Koron(婦人 公論), 1927).As is well known, Akutagawa’s later years of his literary career were marked by an inclination toward the realm of the unconscious and, at the same time, by a sense of “unknowable anxiety” that welled up from within the unconscious. Yoshio Shiozaki calls such a phenomenon “forced thinking,” and the protagonist (myself) of Akutagawa’s later years of literature also feels as if I am a puppet being moved by “someone else’s existence” beyond my own will. It can also be said that Akutagawa’s style in his later years depicts the world of “vague anxiety” of the puppet “I”. “Shinkiro(蜃気楼)”, the subject of this article, is also characterized in this way.Nothing dramatic happens to the main character, “I,” but the mirage he goes to see is overlaid with an eerie image of a new era of melancholy and gloom. The protagonist’s “me” is not a dramatic event, but an image of “something” coming from the other side of the sea toward this side.In the end, however, nothing happens in this work, and only an eerie mental image is left as an aftertaste. This paper examines the method of constructing the world of “Shinkiro(蜃気楼)” with its “vague uneasiness” through the rhetoric of this work, and analyzes it by delving into one aspect of the methodology of Akutagawa’s “novel without a story” of his later years.