Below are 20 commonly asked interview questions in Japanese tech companies. These answers are written from the perspective of a Senior Software Engineer. The STAR (Situation, Task, Action, Result) framework is used where appropriate.
1. Tell me about yourself.
Sample Answer: I'm a senior software engineer with over 10 years of experience, primarily in backend systems and scalable cloud architecture. I've led several cross-functional projects at Amazon, where I focused on performance optimization, system design, and mentoring junior engineers.
2. Why do you want to work in Japan?
Sample Answer: I've always admired Japan's culture of craftsmanship and attention to detail. Professionally, I'm drawn to the unique challenges of building global-scale products in a multilingual, multicultural context. I also see growth potential in Japan's tech scene, particularly in SaaS and B2B innovation.
3. Why are you leaving your current job?
Sample Answer: While I've learned a lot at Amazon, I'm looking for a new environment where I can take on more ownership, possibly in a smaller but fast-moving team, and contribute more directly to product strategy and localization for the Japanese market.
4. Tell me about a challenging project you led.
Sample Answer (STAR):
- S: At Amazon, I led a project to refactor a legacy service responsible for handling 40% of our regional traffic.
- T: The goal was to improve scalability and reduce latency during peak season.
- A: I coordinated a team of 5, introduced load testing suites, and redesigned the service using a microservice-based architecture.
- R: We reduced latency by 35% and enabled 99.99% availability during peak traffic.
5. What are your strengths?
Sample Answer: My strengths are system design, code quality, and cross-team communication. I consistently receive feedback for my clear documentation and ability to make complex technical topics accessible to non-engineers.
6. What are your weaknesses?
Sample Answer: Earlier in my career, I struggled with overengineering solutions. Over time, I've learned to prioritize MVP delivery and iterate based on feedback.
7. Tell me about a time you disagreed with a team member.
Sample Answer (STAR):
- S: During a design review at Amazon, I disagreed with a teammate over using a NoSQL vs SQL solution.
- T: We needed to choose the right DB for a new customer-facing analytics feature.
- A: I proposed we benchmark both approaches using real-world traffic patterns. We presented the findings to the team.
- R: The final solution used a hybrid model that achieved both speed and reliability. We launched 2 weeks ahead of schedule.
8. Describe a time you failed.
Sample Answer (STAR):
- S: A few years ago, I pushed a hotfix deployment late at night without notifying QA or setting up temporary monitors.
- T: I assumed it was a minor change and skipped the usual rollout protocol.
- A: Within hours, we saw a spike in error rates related to a downstream system that wasn't backward-compatible with the fix. I led the rollback, notified stakeholders, and coordinated a war room with the SRE team. I also wrote the postmortem and proposed a deployment checklist revision.
- R: As a result, we added automated rollback triggers, required canary checks even for hotfixes, and significantly improved deployment safety. The checklist I authored is still part of our team's SOP.
9. How do you handle pressure?
Sample Answer: I prioritize ruthlessly, focus on short-term wins, and over-communicate. At Amazon, peak season load tests or outage war rooms are high-pressure by default—I've learned to keep calm and execute in stages.
10. How do you mentor junior engineers?
Sample Answer: I focus on pairing sessions, architectural walkthroughs, and guiding them through design doc writing. I also give feedback through code reviews and quarterly goal-setting.
11. Tell me about a time you improved system performance.
Sample Answer (STAR):
- S: A legacy billing system had frequent slowdowns during monthly batch runs.
- T: I was tasked with reducing processing time and improving overall reliability.
- A: I analyzed query patterns, introduced indexing, parallelized key workflows, and migrated to a newer instance type.
- R: Processing time was reduced by 60%, and batch failures dropped to zero over the next 6 months.
12. Describe a time you managed a conflict on the team.
Sample Answer (STAR):
- S: Two senior engineers had conflicting views about our monitoring stack.
- T: I needed to mediate and get alignment before a key infrastructure rollout.
- A: I facilitated a focused discussion, gathered objective data from production incidents, and built a prototype hybrid dashboard.
- R: We implemented a unified solution that leveraged the strengths of both approaches.
13. How do you stay up to date with new technologies?
Sample Answer: I subscribe to engineering blogs, follow OSS projects on GitHub, attend internal and external tech talks, and try out new tools through side projects.
14. Tell me about a time you led a cross-functional team.
Sample Answer (STAR):
- S: At Amazon, I led a team including PMs, QA, and infra to launch a new internal debugging platform.
- T: We needed to unify debugging across 6 different microservices.
- A: I scoped MVP, aligned timelines across stakeholders, and led 2-week sprints with demos.
- R: Reduced mean time to resolution (MTTR) by 25% and improved dev satisfaction in our post-launch survey.
15. How do you handle vague or ambiguous requirements?
Sample Answer: I proactively clarify through stakeholder interviews, define edge cases with user stories, and document assumptions. I prefer shipping a thin slice and iterating quickly.
16. What do you do when you're stuck on a technical problem?
Sample Answer: First, I isolate the problem and try to reproduce it reliably. If I hit a wall, I escalate intelligently—either by pairing with a teammate, reviewing related design docs, or checking for similar issues on Stack Overflow or GitHub. I also document what I've tried so far to make collaboration easier.
17. Describe a time you made a decision without full information.
Sample Answer (STAR):
- S: During a system outage, we didn't yet have a full RCA but needed to restore service quickly.
- T: I had to decide whether to failover to a backup region with known latency tradeoffs.
- A: I consulted with SRE, checked recent metrics, and made the call to failover.
- R: We restored partial service in under 30 minutes, minimizing user impact. Postmortem review validated the choice.
18. How do you ensure code quality in a fast-paced environment?
Sample Answer: By investing in strong CI/CD pipelines, enforcing code review best practices, and encouraging unit/integration testing. I also set code ownership clearly so quality doesn't become "someone else's problem."
19. What is your approach to documentation?
Sample Answer: I write architecture-level docs upfront, maintain API specs via tools like Swagger, and ensure that README files are always current. For onboarding, I often create internal wikis and code walkthrough videos.
20. Tell me about a time you onboarded to a complex codebase.
Sample Answer (STAR):
- S: When I joined Amazon, I had to work on a payments microservice handling millions of requests daily.
- T: I needed to contribute within the first month despite no prior fintech background.
- A: I started by reading runbooks, tracing logs, and shadowing senior devs. I also created sequence diagrams to visualize key workflows.
- R: Within 3 weeks, I shipped my first feature and later onboarded 2 new hires using the same resources I compiled.