【Blockchain Engineer】Fintech Service using blockchain technology / Full Remote/ Business Japanese

As a Blockchain Engineer at this company, you will design, develop, and operate blockchain-related systems for a new fintech business building next-generation financial infrastructure. You join a core team from the launch phase, working across blockchain, backend, and infrastructure to create a globally deployed system that balances speed, quality, and security. You will help shape technical policies, development frameworks, and design principles while collaborating with Product Managers and engineers across domains.

What you'll do

• Design, develop, and operate blockchain-related systems
• Design and develop smart contracts
• Research and implement new technical domains
• Ensure system scalability, maintainability, and security
• Define requirements and specifications, and build consensus with stakeholders on ambiguous requirements in new domains
• Build development frameworks that balance speed and quality, including highly available APIs, optimized cloud infrastructure, CI/CD pipelines, and documentation
• Contribute to technology selection and proactively shape the team's development processes

What you bring

• Development experience demonstrating foundational implementation skills: either with libraries, frameworks, and middleware, or in technically challenging environments such as high-load systems (social games, ad tech), high-reliability systems (data infrastructure, FinTech), or distributed systems (Blockchain, IoT)
• Fundamental knowledge of software development including algorithms, data structures, networking, security, and design patterns
• Product development experience with blockchain technology, such as smart contract design and implementation (Solidity, Rust), blockchain node construction and operation, wallet integration or key management, or development of blockchain-powered services (Web3, DeFi, NFT)
• Experience designing and operating systems using major cloud services (AWS, GCP, or Azure), including managed services such as computing, storage, databases, networking, serverless, containers, and messaging
• Business-level Japanese
• Ability to understand system-related English literature and apply it to implementation

Nice to have

• Deep knowledge in blockchain and cryptography, including Zero-Knowledge Proofs (zk-SNARKs, zk-STARKs), Multi-party computation (MPC), homomorphic encryption, token design, or smart contract security audits
• Expertise in Layer 2 / Rollup technologies, distributed consensus algorithms (PoS, BFT), or signature/cryptography/identity management (Passkey, ECDSA, BLS signatures, ECIES)
• Development experience using strongly typed languages such as Go, Rust, Kotlin, Java, C#, or C++
• Frontend experience with React or Vue
• Backend experience with frameworks such as Express, Koa, Spring Boot, or Ktor
• Experience designing and building cloud environments using IaC tools (Terraform, CloudFormation)
• System development and operations experience in the financial sector
• Design, operation, and analysis of large-scale data
• Development experience with IoT/devices (Raspberry Pi, Arduino, M5Stack)

What we offer

• Annual salary of 8 million yen to 15 million yen
• Fully remote work with flextime system
• Full social insurance
• Commuting allowance
• Stock options
• High-spec MacBook Pro provided every two years
• Choice of keyboard, mouse, and chair (Ergohuman or Contessa)
• Side jobs permitted (personal service development, technical advisor roles)
• Book purchases covered up to 10,000 yen per month
• Personal cloud environment costs covered up to 10,000 yen per month
• Access to employee library with O'Reilly's latest publications
• Lounge work environment with sofas and standing tables
• Unlimited coffee
• Conference participation expenses covered, including lodging and travel
• Qualification assistance up to 30,000 yen for work-related certifications
• Saturday, Sunday, and national holidays off
• Annual paid leave, New Year holidays, and summer holidays

About the company

Founded in 2018, the company creates value through technology by implementing blockchain in society. It conducts proof-of-concept projects, business planning, and R&D with leading Japanese partners in financial and mobility sectors, addressing blockchain challenges in scalability and interoperability. As the financial system undergoes transformation toward digital assets and Real World Assets (RWA), the company is building next-generation global financial infrastructure as a Japan-born, global deep tech company.