Services
Two kinds of systems I build, and the skills behind them. Every service with a page of its own links to the projects and write-ups that show it in practice.
What I Build
Custom Business Systems
Systems a business runs on every day: cases and sales KPIs, verified memberships and approvals, clinical and home-nursing workflows, campaigns matched to devices. Each project page shows which layers I was responsible for. Examples: Dr.Well-B, TaxPal, Waroku Hospital Karte, Waroku Home-Visit Nursing and a multi-tenant Beacon advertising platform.
Corporate & Content Web Platforms
Corporate, brand and campaign websites that marketing teams update themselves through a CMS, served from a CDN, multilingual where needed, with spam-protected forms and security scanning on every change. Examples: the GO taxi website ecosystem, Wonderia YOKOHAMA, Yokohama Stadium and the IR platform of a listed company.
What I Do
Backend Engineering
Building backends and APIs for business systems and high-traffic platforms, keeping data correct and responses fast through query tuning, caching and background jobs for heavy work. Examples: Dr.Well-B, TaxPal, and a Beacon platform that has handled 761,921 device connections in a single hour.
Cloud Infrastructure
Provisioning and managing GCP and AWS infrastructure in Terraform, so every environment can be reviewed and recreated. IAM, secrets, CI/CD and monitoring are in place from day one, which makes each release routine work rather than a risk.
Production Troubleshooting
Finding the real root cause when production breaks and it is unclear whether the application, the cloud or the CDN is at fault, then fixing it and adding the monitoring that keeps it from coming back. Case study: an HTTP 500 that only Googlebot saw.
Security & Reliability
Investigating security incidents, reviewing infrastructure and access, and hardening production: secrets kept out of source code, and vulnerability and leaked-secret scanning (Trivy, Semgrep, Gitleaks) in CI, so risks are caught before they become incidents.
Technical Leadership
Keeping a project technically on course: architecture direction and trade-off decisions, reviews that catch risk before release, mentoring, and leading the team through incidents — as Tech Lead on healthcare, tax and accounting, and enterprise web projects.
Full-stack Web Development
Setting up and maintaining Next.js, React, Nuxt and Vue applications together with the API behind them, and resolving the framework, routing and i18n issues that slow a whole team down — from corporate websites to healthcare systems.