“Sekibetsu” is a novel written by Osamu Dazai, a representative figure of Japanese Buraiha writers, and it is based on “Mr. Fujino” by Lu Xun. It is one of the main adaptation novels in Chinese literature. This paper was prepared in response to a project by the Cabinet Intelligence and Research Office and the Japanese literary newspaper that aimed to materialize the five fundamental principles outlined in the Declaration on Greater East Asia and corresponded to the principle of independence and affinity. First, it probes the reason behind Dazai’s creation based on Shina by investigating the historical context of “Sekibetsu,” along with the Greater East Asia Co-prosperity sphere and the Greater East Asia assembly. By referring to the reception of Lu Xun and his literary works in Japan at that time and the connection between his work and Dazai’s, this paper attempts to explain why Dazai used Lu Xun’s “Mr. Fujino” as the subject. Secondly, this paper filters out the content change made by Osamu Dazai through a comparative study of the content and literary expression of “Sekibetsu” and “Mr. Fujino.” Additionally, it analyzes Dazai’s motives for adopting the novel and the historical background. In conclusion, Dazai conveyed a type of “pure independent affinity” through his novel, which differs from the untruthful slogan in the five principles of the Joint Declaration of Greater East Asia.