Personal Identity is one of the hot topics in Western Philosophy. Among the various interpretations, the Reductionist explanation given by Derek Parfit has had a profound impact. However, his depersonalization of experience is counterintuitive and fails to sufficiently address the controversies surrounding the continued existence of the self, especially in scenarios involving Fission and Mind-Switching—where will I wake up? These conundrums epitomize the challenges faced by Reductionism. To resolve this predicament, we must first clarify the essence of personal identity. This paper begins with this question and then elucidates the specific meaning of the statement ‘I am X’—it signifies that ‘I am perceiving things from X’s first-person perspective’. Adopting this internal, first-person perspective, we re-examine the cases offered by Parfit, Williams, and others, reanalyzing their reductionist strategies. Our purpose is to address the fundamental controversies within philosophical literature and ultimately provide a complete explanation of the continued existence of the self over time.