Rails developer in Osaka. I build things and then keep them running.

10 years in Japan, working day to day in Japanese. I develop Kengaku Cloud at Biz Creation, and outside that I run two products of my own — one for Japanese Pension refunds, one documenting my 8 years of reviewing ramen.

Work

Independent products I build and operate, alongside team-based product work.
A My Pension Japan claim moving through review and filing

My Pension Japan

Pension refund claims

People leaving Japan are owed their pension contributions back, but the application is cumbersome for non-Japanese speakers, and the tax portion is legally restricted work. My Pension Japan connects them to the professionals licensed to do it: a Labor and Social Security attorney files the pension claim, a tax accountant handles the tax. It runs everything around that in one place: intake, documents, signatures, payment. It is live in private beta, with multiple paying customers moving refunds through it before any marketing.

  • Licensed filings routed to a labor attorney and a tax accountant — separate records, separate reviewers
  • Stripe checkout with an upfront fee plus commission split
  • Generated pension forms — coordinate-mapped PDF overlays
  • E-signatures, staff review queues, and end-to-end audit history
  • Self-managed infrastructure in Japan — data residency, automated encrypted backups, and regularly tested recovery
Rails 8 · Hotwire
Soren Umstot
Osaka, by way of San Diego

Off the clock

Outside the editor
  • StudyingWorking toward JLPT N1, and learning Go
  • BuiltA Raspberry Pi e-ink board showing ITM and KIX arrivals
  • Dialing inEspresso on a Silvia Pro X
  • Reading The Odyssey — Homer Updated from Goodreads

Ramen Ranger

Ramen reviews, mostly Kansai

My own ramen site: every bowl I've reviewed since 2018, mostly Kansai and wherever else in Japan I end up. Scored, photographed, and mapped. Readers can sign up to favorite bowls and leave comments. It publishes a JSON API, which is what fills the row below.

theramenranger.com
264 reviews
2018 hunting since
Rails 8 Turbo, Kamal, Hetzner

Latest five from my API, with a build-time fallback. Browse the reviews

Kengaku Cloud

Biz Creation — 2023 to present

A cloud platform used by Japanese home builders and real estate firms. I work on a long-lived Rails codebase with a team of three: new features, third-party integrations like the Google Calendar API, bug fixes, and performance tuning. I also help define the team's practical workflow for using AI tools to deliver faster while maintaining code-quality standards. The whole environment is Japanese: specs, code review, and working directly with sales and customer success.

Ruby on Rails · AWS · Heroku · legacy refactoring · 日本語業務

Where I started

2021 — 2022

A Rails chat app on ActionCable, a React crypto portfolio calculator, Ozei (a team project that helps large groups find restaurant reservations), and a few Python games. My bootcamp year and the months after. The production work since is closed source, so this is what's public.

github.com/sumstot

How I work

Rails 8's minimal setup, deployed with Kamal to servers I manage myself when the choice is mine — I'd rather know exactly what is on the machine than debug a platform I can't SSH into. When a project already runs on AWS, I work there too. For products I operate, staging mirrors production.

Application

  • Ruby on Rails 8
  • Hotwire — Turbo, Stimulus
  • Solid Queue, Solid Cache, Solid Cable
  • SQLite + Litestream, PostgreSQL
  • JavaScript, Python

Infrastructure

  • Kamal, Docker
  • Vultr, Hetzner, Heroku
  • AWS — S3, RDS, CloudFront, CloudWatch
  • Cloudflare CDN and WAF
  • Backblaze B2, Litestream backups

Working together

  • One developer from build through deployment, or embedded in your team
  • Stabilizing and improving an existing Rails application
  • Deployment with documented operating and handover steps
  • Ongoing maintenance
  • English or 日本語