Full stack engineer with conversational Japanese language

This is not a role where you simply take over an existing codebase or work within a narrowly defined technical area.

You will have the opportunity to own the product lifecycle end-to-end—from understanding business requirements and defining specifications to architecture, implementation, deployment, and operations.

Our product covers the entire workflow from:

Ordering → Design → Payment → Manufacturing → Logistics

You will work across these areas and help determine how the system should be designed as we scale globally.

Because our current product was initially developed during the MVP phase with external development partners, you will also have the opportunity to review, redesign, and rebuild existing components when necessary.

What You Will Do

Full-Stack Product Development

• Design, develop, and operate product features across the frontend, backend, and infrastructure.
• Take end-to-end ownership of business workflows spanning ordering, payment, manufacturing, and logistics.
• Build scalable systems that can support CUSTA's global expansion.

Architecture & Technical Decision-Making

• Participate in designing the overall platform architecture.
• Make decisions regarding technologies, system design, and technical trade-offs.
• Review existing architecture and determine when components should be redesigned or rebuilt.

AI-Native Development

• Use AI coding tools such as Claude Code, Cursor, GitHub Copilot, and Gemini as part of your daily development workflow.
• Help define what should be delegated to AI and what should remain under human architectural and engineering control.
• Establish engineering guardrails such as typing, testing, code review, and development standards.

Product & Business Collaboration

• Work closely with the CEO, Product Managers, designers, and business teams.
• Participate in product and feature definition from an early stage.
• Translate business and operational challenges into technical solutions.
• Collaborate with manufacturing partners and the Malaysia-based team.

Engineering Organization Building

• Help establish engineering processes and development workflows from the ground up.
• Contribute to building a highly productive, AI-native engineering culture.
• As the team grows, there may be opportunities to take on technical leadership responsibilities.

Development Process

• Agile development process
• 1-week development sprints
• Product priorities and project structures are defined on a quarterly basis
• Close collaboration with Product Managers and designers
• Engineers are encouraged to proactively propose technical approaches that create business value

Tech Stack

Languages

• TypeScript
• Node.js
• Ruby

Frameworks & Libraries

• Vue.js
• Nuxt.js
• NestJS
• GraphQL
• Tailwind CSS
• Ruby on Rails

Database & Storage

• MySQL
• Amazon Aurora
• ElastiCache
• Amazon S3

Infrastructure

• AWS
• ECS Fargate
• Lambda
• AWS CDK
• SQS
• Supabase
• Terraform
• Docker

Monitoring & SRE

• Datadog
• Sentry
• CloudWatch

CI/CD & API

• GitHub Actions
• CircleCI
• Postman
• Swagger / OpenAPI

AI & Development Tools

• GitHub Copilot
• Cursor
• Claude
• Gemini

Design & Collaboration

• Figma
• Slack
• Notion
• GitHub Wiki

Required Qualifications

• Professional experience developing products as a Full-Stack Engineer
• Hands-on experience implementing both frontend and backend systems
• Experience with TypeScript or React / Next.js
• Experience using AI coding tools such as Claude Code, Cursor, GitHub Copilot, or similar
• Basic knowledge of databases, networking, and security
• Conversational-level Japanese
• Ability to read English technical documentation
• Willingness to communicate and collaborate in English

For candidates who are not Japanese citizens

Candidates must already have valid authorization to work in Japan at the time of application.

Preferred Qualifications

• Experience with NestJS, GraphQL, or Prisma
• Experience building and operating infrastructure on AWS
• Experience implementing LLMs, AI agents, RAG, or other generative AI technologies into products
• Experience as a Tech Lead or leading engineering projects
• Experience developing products at an early-stage startup or during a new business launch
• Business-level English communication skills
• Experience working with international teams

Who We Are Looking For

We are looking for someone who:

• Is excited about building a global startup from an early stage
• Enjoys taking ownership and making technical decisions independently
• Wants to work across the entire product development lifecycle
• Is highly interested in both business and technology
• Enjoys solving real-world operational problems through technology
• Is comfortable working in an environment where requirements and organizational structures are still evolving
• Continuously learns new technologies and actively experiments with AI development tools
• Is willing to work hands-on and move quickly in a startup environment
• Shares our values: