This paper aims to investigate Yisaengsong’wŏllok(A Record for redressing Mr. Yi’s grievances) in comparison to a newly found manuscript, Yuyŏnchŏn Husŏ(Afterword to the Biography of Yuyŏn) included in Yuyŏnchŏn, held by Kyemyŏng University library. Yuyŏnchŏn Husŏ which has been known by its title without contents offers valuable information and insights into the understanding of Yuyŏnchŏn written by Yi Hangpok: first, the author of Yuyŏnchŏn which blames Yi Ji, Yu Yŏn’s brother- in-law, doubted the culpability of Yi Ji; second, the impersonator Chae Ŭngkyu was extremely successful in impersonating Yu Yu, Yu Yŏn’s elder brother, hence many people were bewildered by Chae’s fraud, which exculpates Yi Ji’s intentional framing of Yu Yŏn. Also, ‘Yuyŏnchŏn Husŏ’ allows specifying the year Yisaengsong’wŏllok was written, which is after 1609. Yisaengsong’wŏllok elaborates Yuyŏnchŏn Husŏ by focusing on the following points: Yu Yŏn himself once misrecognized Ch’ae Ŭngkyu as his own brother, which is silenced in Yuyŏnchŏn. These features imply that we need to take the historicity of literary texts more seriously rather than solely focus on aesthetic aspects of a given text.