Language Engineer – Compiler & Programming Languages | Fast-Growing AI & Cloud Data Transformation Company

Job Description We are currently partnering with a fast-growing AI & Data consulting company in Japan that is actively expanding its AI & Data division and is now looking for a Language Engineer specializing in Programming Languages, Compiler Technologies, and Program Analysis. Please note that prior financial industry experience is NOT required. Annual Salary: ¥10M – ¥22M JPY JAPANESE BUSINESS LEVEL REQUIRED The company works directly with major financial institutions and enterprise clients in Japan, supporting large-scale digital transformation, AI implementation, data modernization, and legacy system transformation initiatives. This position is part of the development team behind a proprietary AI-powered legacy modernization product designed to help financial institutions analyze, understand, and modernize large-scale legacy systems. Financial institutions often operate complex core systems built over multiple generations using programming languages such as COBOL, PL/I, Java, C/C++, SQL, and Shell. The company is now developing a language-independent analysis and transformation platform capable of handling these complex, multilingual codebases at scale. As a Language Engineer, you will play a core technical role in designing and implementing the programming language infrastructure behind this platform, including parsers, Abstract Syntax Trees (AST), Control Flow Graphs (CFG), Intermediate Representations (IR), static analysis systems, and cross-language code transformation technologies. You will also contribute to the technical foundation that enables Large Language Models (LLMs) and other AI technologies to understand, analyze, and transform complex enterprise source code. The environment is highly technical and collaborative, working closely with Software Engineers, Product Managers, AI specialists, and consultants. This is an excellent opportunity for engineers who want to work on deep technical challenges at the intersection of Programming Languages, Compiler Technologies, Program Analysis, Legacy Modernization, and Generative AI. Rather than focusing on a single programming language, this role offers the opportunity to build the core technology for a language-independent modernization platform capable of analyzing and transforming large-scale, mission-critical enterprise systems. Key Responsibilities • Design and implement multilingual source-code analysis infrastructure • Design and develop parsers for multiple programming languages • Design Abstract Syntax Trees (AST), Control Flow Graphs (CFG), and Intermediate Representations (IR) • Develop language-independent program analysis frameworks • Design and implement static analysis and structural code analysis capabilities • Build call graph, dependency analysis, and code relationship analysis systems • Develop abstractions and visualization mechanisms for large-scale legacy codebases • Design validation mechanisms to ensure consistency before and after code transformation • Develop cross-language code transformation engines • Implement automated refactoring and source-code transformation capabilities • Design language infrastructure enabling AI/LLM-based code understanding and generation • Contribute to architecture design for AI-integrated legacy modernization platforms • Collaborate with engineers, Product Managers, and consultants on product development and technical strategy Examples of Technical Challenges • Analyzing large-scale financial systems containing COBOL, PL/I, Java, C/C++, SQL, Shell, and other languages • Building multilingual parsing infrastructure from the ground up • Designing language-independent AST / IR architectures • Implementing scalable static analysis and dependency analysis systems • Developing automated legacy code transformation and refactoring technologies • Building compiler and program-analysis technologies as part of a commercial product • Integrating LLMs with structured source-code analysis systems • Developing scalable modernization infrastructure for mission-critical enterprise systems Requirements Requirements Required: • Professional experience in programming language processing, such as Parser development, AST manipulation, static analysis, or code transformation • Experience designing or implementing systems using Abstract Syntax Trees (AST) and/or Intermediate Representations (IR) • Strong understanding of the syntax and type systems of multiple programming languages • Experience analyzing, refactoring, or transforming large-scale codebases • Ability to clearly communicate technical design concepts and discuss architecture and implementation approaches with other engineers Benefits Benefits Compensation & Work Style: • Annual salary: ¥10M – ¥22M JPY • Location: Nihonbashi, Chuo-ku, Tokyo • Hybrid work style available (office + remote work combination) • Full flex-time system with no core hours • Standard working hours: 8 hours/day • Average overtime: approximately 20–30 hours/month • Salary review available • Performance-based bonus generally paid twice per year (June and December) Holidays & Time Off: • Full two-day weekend system • 123 annual holidays • Paid leave granted after the probation period • Refresh leave • New Year holidays • Parental leave • Condolence leave Benefits: • Defined contribution pension plan • Learning and self-development support • Internal/external networking support budget • Sports & wellness allowance • Annual health check support • Full influenza vaccination support including dependents • Full transportation reimbursement • Relocation support for eligible employees • Childcare/babysitter support • Business trip and training allowances