Job Advert Title: Software Engineer (Backend)
Location: Nihonbashi, Tokyo
Division: DigitalX
Employment Class: Permanent
Description
【募集の背景 / Purpose & Scope】
We are looking for an ambitious backend engineer to help shape the future of Astellas by building the production backbone of our Generative AI platforms. This is a high-impact role at the heart of our digital transformation, where you will design, deploy, and scale systems that enable cutting-edge AI to make a tangible difference across commercial, manufacturing, and medical operations.
In this role, you’ll own the challenge of bringing state-of-the-art AI into production, integrating diverse data sources, architecting resilient APIs, and ensuring scalable, reliable service delivery at enterprise level. You’ll have the autonomy to make big decisions, continuously improve systems, and explore new technologies while collaborating with a dynamic, globally distributed team of innovators across multiple time zones.
This is more than backend engineering. it’s an opportunity to drive real transformation at scale, experiment with SOTA AI, and grow in an environment that values continuous learning, global collaboration, innovation, and impact.
【職務の内容 / Essential Job Responsibilities】
（雇入れ直後）
・ API Development & Integration: Build and scale secure RESTful and GraphQL APIs that power Generative AI applications, enabling seamless integration between AI models, data pipelines, and user-facing products.
・ Production-Grade AI Deployment: Lead the design and deployment of backend systems that bring state-of-the-art Generative AI into production, ensuring performance, scalability, and enterprise-grade reliability.
・ Data Engineering & Integration: Manage diverse data formats and integrate with SQL/NoSQL databases, vector stores, and streaming platforms to optimize data ingestion and retrieval for AI-driven use cases.
・ MLOps & DevOps Automation: Develop CI/CD pipelines, implement containerization (Docker/Kubernetes), and automate deployment workflows to accelerate experimentation, continuous improvement, and reliable delivery of AI-powered services.
・ Collaboration & Technical Leadership: Partner with data scientists, ML engineers, and product teams to translate cutting-edge research into production-ready systems; mentor teammates and champion best practices in backend and AI engineering.
・ Monitoring, Reliability & Continuous Improvement: Establish observability, monitoring, and alerting for backend and AI workloads; diagnose issues proactively; and drive continuous optimization of performance, cost, and developer experience.
（変更の範囲）
会社内での全ての業務
【就業環境に関する要件 / Specific Physical or Environmental Requirements】
At Astellas we recognize the importance of work/life balance, and we are proud to offer a hybrid working solution allowing time to connect with colleagues at the office with the flexibility to also work from home. We believe this will optimize the most productive work environment for all employees to succeed and deliver. Hybrid work from certain locations may be permitted in accordance with Astellas’ Responsible Flexibility Guidelines.
【応募要件 / Qualifications】
＜必須 / Required＞
・ Education: Bachelor’s degree in Computer Science, or a related technical field (or equivalent practical experience).
・ Backend Engineering Expertise: Minimum 4 years of professional experience in backend development, with strong proficiency in Python and a track record of delivering production-grade systems.
・ API & System Design: Deep expertise in designing and implementing secure, scalable APIs that power enterprise and AI-driven applications.
・ Cloud Deployment: Hands-on experience deploying, operating, and scaling backend services in cloud environments (AWS, GCP, or Azure), including containerization (Docker/Kubernetes) and infrastructure-as-code.
・ Production-Ready Practices: Proficiency with CI/CD pipelines, automated testing, and monitoring systems to ensure reliable and efficient software delivery.
・ Data Fluency: Strong experience working with structured and unstructured data and integrating with SQL/NoSQL databases, plus familiarity with modern data infrastructure for AI/ML workloads.
・ Scalable Software: Solid grounding in distributed systems, software design patterns, security best practices, and performance optimization at scale.
・ Collaboration & Growth Mindset: Comfortable working in agile, cross-functional teams partnering with frontend engineers, data scientists, and product managers and mentoring peers in backend best practices.
・ Continuous Learner: Demonstrated curiosity and adaptability in adopting emerging technologies, especially in Generative AI, MLOps, and cloud-native development.
＜歓迎 / Preferred＞
・ Generative AI & ML Experience: Hands-on experience contributing to machine learning projects or deploying Generative AI applications (e.g., working with LLMs, vector databases, or model serving frameworks).
・ Cloud AI Expertise: Deeper knowledge of AWS, Azure, or Google Cloud Platform services for AI/ML (e.g., SageMaker, Vertex AI, Azure ML), with experience optimizing cost, performance, and scalability in cloud-native deployments.
・ Data Engineering & ETL: Familiarity with ETL processes, streaming pipelines, and modern data tools for efficient data ingestion, transformation, and integration into AI/ML workflows.
・ Observability & Reliability: Understanding and practical use of application monitoring, logging, and tracing tools (e.g., Prometheus, Grafana, ELK, Datadog) to ensure system health and proactive troubleshooting.
・ Innovation Mindset: Passion for experimenting with emerging frameworks (LangChain, LlamaIndex, Hugging Face, etc.) and applying state-of-the-art research to solve real-world challenges.
【応募書類 / Application Documents】
和文履歴書・和文職務経歴書・英文レジュメ
Both Japanese and English Resumes are needed
【選考プロセス / Selection details】
書類選考 → 1次面接 → 2次面接 → 最終面接
※変更の可能性もございますので、予めご了承下さい。
CV screening → First interview → 2nd Interview → Final interview
*Please be advised that there might be a change in the process.
【勤務地 / Location】
（雇入れ直後）
東京都中央区 アステラス製薬 日本橋事業所 本社
Nihonbashi, Tokyo
（変更の範囲）
会社の定める事業場および自宅
【勤務開始日 / Start Date】
応相談
Will be decided according to the candidate's flexibility
【契約期間 / Contract Duration】
期間の定めなし
Not limited to specified period
【試用期間 / Probation Period】
試用期間原則なし
No probation period in principle
【給与 / Salary】
①基本給：当人の経歴・技術・技能等を考慮して決定
②裁量労働制の場合：裁量労働手当として職務グレードに応じて50,000～100,000円支給
③フレックスタイム制の場合：月間の所定労働時間を超えて勤務する時間に対して時間外勤務手当を支給
①Base salary: will be decided by the candidate's experience, skill and capability.
②When Discretionary Work System is applied: Discretionary work allowance will be paid.(50,000～100,000yen, based on the Grade)
③When Flextime System is applied: Overtime allowance will be paid for time worked in excess of prescribed working hours.
【昇給 / Salary Raise】
有り
【賞与 / Bonus】
有り
【諸手当 / Allowance】
裁量労働手当、住宅手当、通勤手当 等
Discretionary work allowance, Housing allowance, Commutation allowance, etc.
【勤務時間 / Working Hours】
8:45～17:45（月～木）、8:45～16:00（金）、企画業務型 裁量労働制
裁量労働制の場合、所定労働時間を働いたものとみなす
8:45～17:45（Mon～Thu）、8:45～16:00（Fri）
Discretionary Work System
【休日 / Holidays】
完全週休２日制（土曜・日曜）、祝日、5月1日、夏季、年末年始
Weekends(Sat and Sun), holidays, May 1st, summer vacation, New Year holidays
【休暇 / Vacation Leave】
年次有給休暇、育児休業制度、介護休業制度 等
Annual paid leave, childcare leave system, nursing care leave system, etc.
【福利厚生 / Welfare】
雇用保険、労災保険、厚生年金、健康保険、共済会制度、社宅制度、持株会制度、財形貯蓄制度 等
Employment Insurance, Industrial Accident Compensation Insurance, Welfare Pension Insurance, Health Insurance, Mutual Aid Association System, Company Housing System, Employee Shareholder Association System, Property Accumulation Savings System
【アステラス製薬 採用サイト/ Career web site】
https://re-jp.astellas.com/jp/recruit/newgraduates/
For more information about Astellas, please visit our career web site.
"We are an equal opportunity employer and all qualified applicants will receive consideration for employment without regard to race, color, religion, sex, national origin, disability status, protected veteran status, or any other characteristic protected by law."