It is a short story inspired by No. 18, 'Rashomon no uhakoshi ni noborite shinin wo miru nusubito no koto' (a story about a thief who climbed upstairs within the Rashomon gate and saw dead people there) in the "Konjaku Monogatarishu" (The Tale of Times Now Past).
『今昔物語集』の「羅城門登上層見死人盗人語第十八」を題材にした短編小説。