This video episode serves as an expert guide to extinctive prescription (消滅時効) under Japanese Civil Law, specifically tailored for the judicial scrivener exam and incorporating the significant 2020 legal revisions. The core concept introduced is the "5-year/10-year double-route" rule, where a right expires either five years from when the creditor becomes aware of their right (subjective starting point) or ten years from when the right could objectively be exercised, whichever comes first. Crucially, the assertion principle (援用主義) dictates that the expiration of a right only takes effect if the debtor explicitly claims it, preventing automatic judicial recognition.