The short answer
As third-party cookie limits make tracking harder, consent-based first-party data has grown more valuable. Make directly collected customer data the basis for measurement and retargeting.
Collect first-party data with consent at direct touchpoints — sign-ups, purchases, LINE/Kakao friend-adds, newsletters. Clear purpose disclosure and consent are prerequisites.
Collected data underpins segments and lookalikes. Use it within the scope of consent and comply with privacy rules such as Japan's Act on the Protection of Personal Information.
Combined with server-side measurement, it enables relatively stable measurement under cookie limits. The goal is a consistent decision basis, not perfect tracking.