Ego-documents let us hear the voices of those who have been little heard in historiography. Such documents, especially when narrative in nature, provide insight into historical events and periods by illustrating how individuals—in correspondence with their own (in)actions, (in)decisions, and (mis)convictions as well as emotions, fears, aspirations, and frustrations—experienced and perceived these historical phenomena from a contemporary personal viewpoint. Since the revival of narrative historiography in the 1980s, partly in response to the Annales school, such documents have been increasingly recognized and employed as important historical sources. Nonetheless, the terminology for designating the generic nature and encompassing the diversity of such sources, as well as the methodology for historicizing them, remain under debate.