PayPay Card Japan Backend Engineer - Advice / Expectations for System Design (HLD) Round interview

Hey everyone,

I recently cleared the Coding and Low-Level Design (LLD) rounds for a Backend Engineer role at PayPay Card Japan. My next round is the System Design (HLD) round.

For anyone who has interviewed with PayPay / PayPay Card recently or currently works there:

• Problem Types: Do they lean heavily into core fintech/payment problems, or do they also ask general distributed systems questions?
• Key Focus Areas: Are there specific architectural patterns (e.g., Saga pattern, idempotency keys, DB sharding strategies) that they expect you to master?

Any recent interview experiences, tips, or specific topics to prioritize would be hugely appreciated!

Thanks in advance!