Practical guidance for backend architecture, platform engineering, technical hiring, and MVP development—grounded in real production experience across fintech and large-scale distributed systems.
Whether you're building software, hiring engineers, or making important technical decisions, these are the situations I most commonly help with.
Planning a new system, redesigning an existing architecture, or needing a second opinion before implementation.
Validate your technical approach before investing months of engineering effort.
Need an experienced engineer to conduct technical interviews or help calibrate hiring decisions.
Performance, scalability, distributed systems, backend architecture, cloud, and engineering best practices.
System design, backend interviews, engineering career discussions, and practical feedback.
Engineering articles, architecture documentation, technical content, and developer-focused communication.
End-to-end audit of your system architecture, CI/CD workflows, and internal engineering processes. My core is Backend, Cloud & Platform — but I've worked across fintech, payments, marketing tech, and more. I don't touch your code — tell me your scenarios and user journeys, and I deliver a prioritized action plan.
1-on-1 sessions from entry-level career direction to senior/staff System Design mocks. You get structured feedback based on 20+ real interviews conducted at top-tier global payments companies.
Build a prototype from scratch or get an existing one reviewed. I can architect and develop your MVP from zero, or audit your DB schema, API contracts, auth flows, and architecture for issues that vibe-coding tools miss. For teams at any stage.
Deep-dive engineering blog posts, migration case studies, and architecture breakdowns for B2D SaaS companies. Written by someone who has actually built these systems at scale.
I run technical interviews for your hiring pipeline — LLD, System Design, and behavioral — and deliver structured feedback so your team can make confident hiring decisions. Per session.
Re-engineered a personalized asset delivery system, replacing a legacy multi-tenant solution with a streamlined Spring Boot 3.2 (Kotlin) application using coroutines and asynchronous caching. Achieved 8,000 RPS with minimal latency, exceeding peak demand of 7,000 RPS.
Led the migration of 36 Spark-Scala ETL jobs and 51 data lake tables to a new architecture, achieving a cost reduction of 548,000 yen daily (200 million yen annually) while maintaining data integrity and system performance.
Spearheaded the architecture and development of high-throughput, low-latency push notification services handling 120+ million daily notifications for diverse use cases, including transactional and promotional campaigns.
Designed and implemented a timeline notification delivery system from scratch, including drafting, requirements analysis, and implementation with Kotlin, Spring WebFlux, Cadence Workflow, and Kafka integration. Reduced 100 hours per month for the marketing team and increased annual GMV by 4M JPY.
I work on a project basis, not hourly. Clear scope, clear deliverables, clear timeline.
Weekdays
8:00 PM – 12:00 AM (ICT/JST)
Weekends
8:00 AM – 10:00 PM (ICT/JST)
* Time zone is ICT or JST, depending on my current location.
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I'll respond within 1–2 business days.