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We listen carefully to our clients,
think together, and apply uncompromising technical skill.
We build and improve agile IT solutions
that support each client's business growth.
Latest News
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[Award] CTO Tomohisa Takaoka Receives Microsoft MVP Award Again
This year's award is in the .NET area, marking his third award since November 2024.
He will continue contributing to the developer community through open-source development, technical blog posts, and presentations.
Please visit his official Microsoft MVP profile for more information. - [Interview with the President: Part 1] From Tools, Not Finished Products - The President's Starting Point in Making Things
- [Interview with the President: Part 2] From "Extras," Not Finished Products - An Honest Step Ahead, Aiming with a Team That Trusts One Another
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[News] SekibanWasmRuntime is now available on GitHub.
The repository includes source code, documentation, and published artifacts.
Please take a look at this step toward multilingual ES + CQRS. -
[Site Update] We added an Intent-System section to our corporate site.
The section introduces how we preserve intent and connect it to implementation and review in AI-assisted development.
Consultations about Intent-System and AI adoption are also welcome. -
[Site Update] We published the English version of our corporate site.
Our services, technology assets, and company information are now available in English.
We will continue sharing J-Tech Japan's work with customers and partners outside Japan.
Our Services
Agile Development for Products and Business Systems
We provide one-stop support from system planning through development and operations.
Our goal is to keep providing systems that are truly valuable to customers at an appropriate cost.
To achieve that, we develop with the following four values in mind.
- Agile Development
We run development cycles in short one- to two-week intervals, demonstrate working software to clients, and use feedback to decide the next improvements and features together.
- Cloud Utilization
In many recent projects, we build and operate systems on cloud platforms such as Microsoft Azure and AWS. Cloud utilization enables rapid development, lower initial costs, and flexible operations that can grow with the client business.
- EngineerOwnership
We keep asking why a system should be built and what value it should create. Each engineer works proactively to solve the client's essential problems, and we invest in internal education so that our engineers can continue learning modern software technologies and development methods.
- AI Utilization
We see AI as a partner that amplifies engineers' knowledge, and we work to understand both its strengths and its limits. By using AI, we aim to deepen our understanding of client domains, solve complex issues, and provide high-quality products.
- Case Studies
Logi Kintai System Co., Ltd. replaced its attendance system for the transportation industry, "Kintai Driver", with Microsoft Azure. The project was introduced as a Microsoft customer story in November 2022.
The first consultation is free. Please feel free to contact us.
Consulting and Training for Software Architecture
We provide the following services based on practical knowledge of software architecture gained through real projects.
Our consultants and instructors are experienced active engineers who speak at events for engineers in Japan and overseas, write technical books, and actively share knowledge through technical blogs.
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Consulting on advanced design methods such as Domain-Driven Design (DDD), CQRS, and Event Sourcing, as well as AI-assisted development methods
- Introducing advanced methods all at once can stall development. We provide practical proposals that allow teams to adopt them while confirming their effects.
- We provide knowledge for using AI not merely as a code generation tool, but as a safe and effective way to maximize engineers' creativity and productivity.
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Hands-on seminars using Sekiban, an Event Sourcing framework
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We help solve common challenges in adopting Event Sourcing, including lack of specialized knowledge and difficulty applying it in practice.
- Personal support from experienced engineers is available.
- A structured consulting flow with hands-on exercises supports practical system development.
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We help solve common challenges in adopting Event Sourcing, including lack of specialized knowledge and difficulty applying it in practice.
- Case Studies
You can read a PR TIMES case study about our paid hands-on consulting using Sekiban in a real project setting.
Tomohisa Takaoka, our CTO, has received the Microsoft MVP Award again in the .NET area, marking his third award since November 2024. He continues contributing through open-source development, technical articles, and presentations.
For specific programs, we first listen to your situation and propose the approach we believe will be most cost-effective.
Please feel free to contact us.
DX Promotion and Operations Support
We provide hands-on engineering services that work alongside clients as one team to promote DX and support stable operations for companies and local governments.
We provide engineering implementation and support services for a wide range of industries, including local government, pharmaceuticals, and RFID solutions.
If you need more information or support, please feel free to contact us.
Intent-System Intent-Driven Development (IDD)
Preserve intent as the source of truth and connect AI-assisted development to real project workflows.
Intent-System is J-Tech Japan's approach to Intent-Driven Development. Instead of treating a one-time prompt as the source of truth, we keep the reasons, goals, constraints, and decisions of a project as an intent tree, then connect them to GitHub Issues, implementation, review, fixes, and the next development slice.
The currently available OSS product is Intent-Cli, a local-first CLI. It gives AI agents and developers explicit guidance for organizing intents, creating packets, publishing issues, and managing implementation and review loops.
Three anchors for Intent-System
Make intent the benchmark
Capture goals, constraints, trade-offs, and non-goals as an intent tree that can be revisited later.
Turn intent into packets
Create packets from the intent tree and turn them into GitHub Issues that are ready to implement.
Review back against intent
Keep implementation, review, fixes, and closeout aligned with intent while clarifying human and AI roles.
Explore Intent-System in more detail.
Visit the service site for the concept and use cases, and GitHub for the open-source Intent-Cli specifications, documentation, and releases.
Read the background and practical guide on Zenn.
These two articles introduce the concept of intent-driven development and how to work with AI agents in practice.
Sekiban: a design that never deletes data
Sekiban is J-Tech Japan's open-source Event Sourcing / CQRS framework for .NET.
It keeps not only the current state but every change as an immutable event, creating a foundation you can trace, analyze, and reuse later. Sekiban was released as OSS in December 2023. Today, Native DCB is the production-ready path, while SekibanWasmRuntime is opening a newer implementation path.
See a design that never deletes data from three angles
Every change stays visible as structure
Because every change remains as an immutable event, auditability is built into the application model itself instead of being added later from the outside.
Past data can answer new questions later
Event replay makes it possible to revisit history when new questions, analytics needs, or downstream uses appear after launch.
It is easier to hand context to AI
When the why and how of change are structured, the system fits naturally with RAG and broader AI-assisted workflows.
We can help you think through fit, where to start, and what to validate first.
SekibanWasmRuntime
SekibanWasmRuntime makes Sekiban easier to implement. It keeps the core domain-code thinking close to Sekiban DCB while letting you try C# and Rust code inside a Wasmtime sandbox. With published packages and a public container, it creates an easier entry point for newcomers and a practical path for AI-era implementation.
If you want to test the implementation directly, GitHub and the Zenn articles below are the fastest next step.
Related resources
The next step depends on the reader, so the section is split into evaluation material, implementation resources, and ongoing Sekiban updates.
Start with the big picture and evaluation material
This is the best entry point when you want to understand the overall offering or gather material for adoption decisions.
Go deeper through articles and ongoing updates
Use these when you want more implementation detail, background context, and a wider view of Sekiban-related activity.
We can help you sort out where to start, how Sekiban fits your existing development organization, and whether a PoC should come first.
Technology Stack
We use the technologies best suited to our clients' businesses.
Our technology stack is listed on What We Use.
About Us
With offices in Tokyo and New York, we work every day as one team, bringing together engineers and designers around the world.
You can see how we collaborate and how our engineers share technical knowledge on our blog page.
J-Tech Japan, Inc.
| Address | Shinagawa NSS Building 4F, 2-13-31 Konan, Minato-ku, Tokyo 108-0075, Japan |
| Phone | 03-5461-2175 |
| President and CEO | Masaki Yamaguchi |
| External CTO | Tomohisa Takaoka |
| Employees | 31 employees (as of March 2026) |
| Business | System development, maintenance, and operations |
| Capital | 10 million yen |
| Bank | MUFG Bank |
| Shareholder | Japan Technical Software Co., Ltd. |
| Established | April 1, 2008 |
JTS Group
We are a group company of Japan Technical Software Co., Ltd. (JTS), a comprehensive IT company that celebrated its 50th anniversary in 2020.
Japan Technical Software Co., Ltd.
Please feel free to contact us about your project.