Learn in the textbookRules for Handling Personal Information — Consent, Third-Party Provision, and Processing
DefinitionPseudonymization (仮名化) is processing that replaces names and similar details with other codes so that a specific individual cannot be identified unless matched with other information.
ExplanationMatching the data against the lookup table used for the replacement leads back to the original individual, so the processed data still leaves room to identify the person. Under the Act on the Protection of Personal Information, data processed this way according to set standards is called pseudonymously processed information (仮名加工情報), a category created by the 2020 (Reiwa 2) amendment. It is meant for uses such as analysis inside the business and, in principle, cannot be provided to third parties.
AnalogyIt is like an author writing under a pen name. Readers cannot tell who it is, but the publisher's records show the real name.
Memory hookA pseudonym is only a stand-in name; the path back to the real one is kept somewhere else.