Senior Data Test Engineer

On behalf of our Client from Japan, Mobilunity is looking for a Senior Data Test Engineer

Our client is a fast-growing fintech company based in Tokyo that offers its real-time, monthly consolidated credit service all across Japan. Our client started Japan’s first instant post-pay credit service for e-commerce customers in October 2014. The main product is an online payment platform that requires no pre-registration or credit card to use; via this service, the customers can purchase products online using only a mobile phone number and email address and settle a single monthly bill for all their purchases, either at a convenience store, by bank transfer, or auto debit. Customers can use credit funds during a month and then return the balance to zero without paying credit interest.

This service also supports multi-pay installments and subscriptions. There are currently over 4 million accounts in use. This service got the largest investment to date in the Japanese financial tech industry, including a PayPal Ventures investment.

You will work closely with data engineers, analysts, and product stakeholders to validate both real-time data pipelines and batch reporting systems, ensuring that critical financial and operational data remains trustworthy at scale.

This role requires strong analytical thinking, curiosity for systems, and a passion for identifying and preventing data issues before they impact users or business operations.

Key  Responsibilities:

• Collaborate with stakeholders to gather reporting and product requirements and translate them into structured test strategies
• Design and implement automated tests to validate:
  • Data accuracy
  • Completeness
  • Consistency
  • Reliability across real-time pipelines and batch reporting systems
• Analyze test outputs and produce clear, actionable reports on data quality issues, anomalies, and trends
• Partner closely with data engineers, analysts, and developers to integrate testing into CI/CD and development workflows
• Continuously identify improvements in testing methodologies, tooling, and processes
• Experiment with new industry-standard testing tools and provide recommendations for adoption
• Proactively detect data issues and suggest preventive measures to improve system robustness
• Contribute to a culture of quality, ownership, and continuous learning across teams

Requirements:

• Experience working in cross-functional and cross-cultural engineering environments
• Strong experience with at least one programming language (e.g., Python, Scala, Ruby, or similar)
• Solid knowledge of SQL and relational database systems
• Experience testing data systems, pipelines, APIs, or backend services
• Strong analytical mindset with high attention to detail
• Ability to learn quickly and contribute to unfamiliar systems and domains
• Comfortable working in complex, fast-changing technical environments
• Strong communication skills in business-level English
• Willingness to share knowledge, learn continuously, and improve team practices

Nice to have:

• Experience working in security-sensitive or regulated environments (e.g., fintech, payments, banking)
• Business-level Japanese language capability
• Experience with data pipelines, ETL processes, or streaming systems
• Familiarity with observability, monitoring, or data quality tools
• Experience working with distributed systems or event-driven architectures

• Exposure to automation frameworks for data validation or QA pipelines

  English:Upper-Intermediate