This paper investigates the nature of resumption, focusing on the status of a gap in Japanese relativization and topicalization. Taking reconstruction effects as evidence, I adopt the movement analysis of relativization and topicalization. The examination of relativization and two types of topicalization shows a correlation among island-insensitivity, the occurrence of resumptive pronouns, and the absence in a dislocated element of a particle associated with the original position. Based on this correlation, I claim that Japanese resumptive pronouns are introduced in the PF component in order to repair a stranded particle. Given this analysis, resumption and island-insensitivity in certain environments in Japanese, as well as the difference in the behavior of resumptive pronouns between Japanese and English, are accounted for.