Websites and landing pages
Company sites, product pages, and campaign pages. Launch small, then grow it.
Website design & business systems
Websites that communicate.Systems that simplify work.
From websites and landing pages to booking and admin apps and workflow automation. I clarify the goal and the people using it, then handle strategy, design, development, launch, and operation directly.
Simple website or landing page First project JPY 0 Free subdomain · once per customer · 30 places in total ↗
01 WEBSITE & LP02 BUSINESS SYSTEMS03 SHOPIFY APPSTOKYO / REMOTE
Design & development
What I can build
Your idea does not need to be finished. We start from what is actually slowing you down.
Internal tools and web apps
Booking, membership, and data management — the tools your team actually opens every day.
An end to daily manual work
Copying, totalling, notifying, and the spreadsheet open all day. Work a person should not have to do.
Shopify apps
Turn a problem in your store into an app that runs inside the Shopify admin — including submission for App Store review.
Inventory and purchasing on autopilot
Replace the spreadsheet-and-instinct routine with numbers that arrive on their own.
Japanese compliance
Qualified invoices, e-bookkeeping retention, and commercial-law disclosures — the parts overseas apps do not cover.
SELECTED WORK
Products I have built and continue to operate
Alongside client work I build and sell my own products — planning, design, development, store review, and operation, all handled by me. Here is what each one actually does.
01
UreyukiBox
Demand forecasting & inventory planning
02
DenchoBox
Japan compliance automation
03
Palette Studio
Pharma-law-safe AI content
Operator & proof
My own products are the proof that I can build
I plan, design, and build Shopify apps, take them through App Store review, and run them in production on my own. Before that came a trust bank’s reporting platform — detailed design, APIs, tests, and the client-facing role — and before that, electrical design for nuclear plant equipment, where precision is not optional.
See the founder profile and business details- Live on the App Store
- A Shopify app reviewed, published, and running (UreyukiBox)
- About 10 years in engineering
- Electrical design (nuclear plant equipment) → software. More than five of those in software development
- 9 months → about 5
- Delivery time cut on a trust bank platform (previous role)
- About 20 sec → under 1
- Page-transition performance improvement (previous role)
The delivery and performance figures come from individual projects handled in a previous role and do not guarantee the same outcome for every project.
How projects work
Starting small keeps the first step light
We do not build everything at once. The most painful part goes first, as something that actually runs, and we add to it while you use it. You speak to the person who writes the code, so nothing is lost in relay. Pricing is quoted individually once I understand the work.
- 01The same person, start to finish
Sales and engineering are not separate people here. The person who hears the problem is the one who builds it.
- 02Building less is the real discount
Not building unnecessary features is the biggest saving available. I will point out what your goal does not need.
- 03Extras always agreed first
The quote states what is included and what is not. Work is never added to your invoice without asking.
Website design
A page designed aroundthe character of the business.
Structure starts with the goal, audience, and real material — not a pre-built template. The first qualifying simple site is free on a free subdomain, with 30 free-build places in total.
See samples and termsOperator
The person you briefis the person who builds.
Mumu Labo is the trade name under which Mai Sato builds software single-handedly, focusing on the Japanese business practices, regulations, and language that overseas apps tend to overlook — and on tools that stay useful for years.
Read the business profileIndependent coverage
Media mentions
2026-08-04UreyukiBox: streamlining purchasing and reordering on Shopify (Japanese)↗2026-08-0482 Shopify apps for Japanese stores (Japanese)↗2025-03-2620 useful Shopify inventory management apps for 2026 (Japanese)↗
The linked articles are written in Japanese.
Notes
Notes
Selling into Japan on Shopify — the compliance work nobody warns you about
Japanese e-bookkeeping rules, qualified invoices, and pricing-display law all apply to overseas merchants selling into Japan. Here is what actually has to change in your Shopify store.
Enquiries
Tell me what is slowing you down
One short form is enough, and asking costs nothing.
Frequently asked questions
The questions we hear most often before a project starts. Anything else — just ask.
- How much does a project cost?
- A simple website or landing page published on a free subdomain (e.g. yourshop.pages.dev) is JPY 0 for your first one, hosting included. After that it starts at JPY 11,000 incl. tax, and a custom domain is billed at cost. SaaS, apps, Shopify, automation, and AI/API integrations are quoted individually based on scope.
- Who does the work?
- The founder, directly. Planning, requirements, design and development, API work, testing, launch, and post-launch improvement are all handled by the same person — which keeps decisions close to the implementation and overhead low.
- Can I get in touch before the idea is fully formed?
- Yes. Support starts at the planning stage: we go through the problem and the goal, propose what to build and how to get there, then design and build only the scope that is needed.
- What kinds of work do you take on?
- Websites and landing pages, SaaS and web/mobile apps, Shopify and e-commerce, internal tools and automation, applied AI, and API/third-party integrations.
- How does a project run?
- Planning and proposal, then requirements and design, then development, APIs, and testing, then launch, operation, and improvement. The scope and assumptions are written into the quote, and nothing is added without agreement. Timelines depend on scope and are given with the quote.
- Can you maintain the site or app after launch?
- Yes — post-launch fixes, maintenance, and the next round of improvements based on how the product is actually used. If something falls outside the agreed scope, you hear the scope and the assumptions before any work starts.
- Do you build your own products?
- UreyukiBox, an inventory and purchasing app for Shopify, is live. DenchoBox (Japan compliance automation) and Palette Studio (pharma-law-safe AI content) are in preparation.