【No Japanese required】Seinor Software Engineer

＜Summary＞

Position:

Salary: ￥7M～11M

Location: Tokyo

【Company Profile】

We are a startup with an ambitious mission: to grow Japan’s GDP and create a society where people can look forward to a better tomorrow.

We aim to overcome the challenges currently facing Japan—such as low labor productivity and a pervasive sense of economic stagnation and confinement—by delivering high-quality, world-class products that provide genuine value to society.

【About the position】

We're looking for a Senior Software Engineer who is passionate about building reliable, scalable, and maintainable systems — from backend business logic to frontend user experiences.

You'll work primarily with TypeScript, with React / Next.js on the frontend and NestJS / Prisma on the backend. You'll collaborate closely with both engineers and non-engineers (product, design, biz/ops) to ship features that power the core of our product for some of Japan's largest enterprise customers.

Our Tech Stack

TypeScript everywhere;

Node.js;

NestJS / Prisma / PostgreSQL on the backend;

React / Next.js on the frontend, React Native (Expo) on mobile; and

AWS (EKS, S3, Lambda); and

Redis.

・Responsibilities

Design and deliver features end-to-end across the stack (frontend, backend, architecture).

Take ownership of technically challenging projects, such as refactoring, complex data modeling, or new platform integrations.

Drive improvements in system reliability, performance, and maintainability.

Mentor other engineers and champion high standards in code quality and architecture.

Participate in support rotations to investigate bugs and incidents.

We value engineers who care deeply about technical quality, end-user experience, and long-term stability — not just shipping tickets fast.

・How we use AI in development

We are bullish on AI as a development tool, and provide free usage of AI tools like Claude Code for our engineers. We have an internal AI task force responsible for policy, guidelines, oversight, and technology in order to empower our engineers to use AI safely and efficiently.

【Requirements】

・7+ years of professional software engineering experience.

・Significant experience with TypeScript.

・2+ years of hands-on work with React (or a similar modern frontend framework).

・Strong understanding of backend frameworks, database modeling (SQL/Prisma), and asynchronous app architecture.

・Proficiency collaborating across functions (product, design, operations, and stakeholders).

・Track record of delivering production systems with an emphasis on scalability, reliability, testability, and maintainability.

・Familiarity with modern development workflows: Git, PR reviews, CI/CD, and automated testing.

Be located in, or be willing to relocate to, Japan (we will support relocation).

【Conditions】

・Annual salary: 7,000,000 JPY – 11,000,000 JPY

・Flextime system (core hours: 11:00 – 16:00)

・Social insurance: Employees' Pension, Health Insurance (including Long-term Care Insurance), Employment Insurance, and Workers' Compensation Insurance

・Year-end and New Year holidays (December 29 – January 3)

・Annual paid leave (granted upon joining; allocated in the month of hire)

・Leave for ceremonial or bereavement purposes

・Various types of leave: Pre- and post-natal, childcare, family care, etc.

・Commuting allowance (up to 50,000 JPY per month)

・Ceremonial and bereavement solatium payments (subject to specific criteria)

・Periodic health check-ups (subject to specific criteria)

・Company-provided PC (not applicable to independent contractors)

・Subsidies for new-hire welcome lunches and team-building social events

・20% cashback program for spending on the Mitsumore platform

・Babysitting discount program

・In-office convenience store/snack service

・Provision of Cursor (for engineers)