Job Description: About the Organization Cyber Defense Operations is the core department responsible for ensuring the safety and security of Rakuten Group's internet services. The Detection Engineering Section is tasked with architecting and building next-generation detection pipelines to defend critical infrastructure against autonomous, AI-driven attacks and sophisticated APTs. We lead the transition to a Detection-as-Code (DaC) model, utilizing eBPF-based runtime security, behavioral analytics, and LLM-integrated pipelines to deliver high-fidelity, actionable alerts. We are "defenders with an attacker's brain," committed to proactive, intelligence-led defense. Job Duties Detection-as-Code (DaC) Transformation: Build and manage an end-to-end detection pipeline featuring peer reviews, version control (Git), and a reusable repository of detection rules. AI/LLM-Driven Detection: Architect and develop AI/LLM-based models to identify autonomous AI attacks. Use AI to automate log onboarding, normalize data, and filter "garbage logs" to drastically reduce SOC noise. Advanced Runtime Security: Lead the implementation of kernel-level monitoring using eBPF-based tools to provide deep visibility into containerized (K8s) and Linux-based workloads. Offensive Security & Threat Hunting: Perform continuous attack simulations (Red Teaming) to validate detection coverage. Lead proactive threat hunting initiatives informed by CTI and the MITRE ATT&CK/FIGHT frameworks. Deception & Defense-in-Depth: Deploy and manage deception technologies to create high-interaction traps. Ensure detection logic aligns with our defense-in-depth architecture. Cross-Functional Orchestration: Collaborate with DFIR, CTI, and SOC teams to ensure CTI is actively integrated into detection logic via AI-driven automation. AI Guardrails & Security: Oversee the security of our own AI/LLM models, implementing guardrails to prevent model poisoning, prompt injection, and adversarial manipulation. SOAR Integration: Partner with the SOC team to ensure detection logic feeds seamlessly into SOAR playbooks for machine-speed response. Minimum Qualifications Experience: 10+ years in Cyber Security, with at least 5+ years in Detection Engineering or Security Research. Detection Engineering: Deep expertise in building detection pipelines, tuning logic for high-fidelity alerts, and managing the security rule lifecycle. AI/ML/LLM Proficiency: Practical experience building/tuning models for anomaly detection and log analysis. Technical Depth: Expert-level coding skills (Python, Go, or Rust) and mastery of Linux/Windows/Mac internals. Container & K8s Security: Strong hands-on experience securing Kubernetes clusters, container runtimes, and microservices architectures. Domain Knowledge: Understanding of Telco networks/protocols (e.g., 5G core, signaling) and Network Security (packet analysis, perimeter/internal controls). Offensive Mindset: Experience in penetration testing, exploit development, or red teaming. Education: Bachelor's or Master's degree in Computer Science, Cyber Security, or equivalent. Certifications: Relevant certifications (e.g., OSCP, GREM, GCFA, CKS, BTL2, or AI-Security credentials). Preferred Qualifications Experience with Infrastructure as Code (Terraform, Ansible, Crossplane). Deep experience with eBPF tools (e.g., Tetragon, Falco, Cilium, Spyderbat). Active contributor to open-source detection projects (e.g., Sigma, YARA, or custom AI-detection models). Experience in high-scale environments (Telco, Cloud-Native, or FinTech). Work Environment Department: Detection Engineering Section, Cyber Defense Operations. Collaboration: Work with diverse teams including security researchers, threat hunters, and AI/ML specialists. Tech Stack: Python/Go/Rust, Kubernetes, Linux, eBPF, Git/Sigma/YARA, LLM-integrated pipelines, SOAR, Terraform/Ansible. Location: Japan (Tokyo or Osaka). Domestic/overseas business travel and relocation may be required. Languages: English (Overall - 3 - Advanced) Looking for members to join our mobile phone business “They cannot succeed if they step into the field at this late date” Some people say Rakuten is reckless in trying to enter the mobile communications business. However, innovation is realized if we succeed when something seems impossible. At Rakuten, we think the world changes when we achieve such changes. Because our history has always been a series of innovations since our establishment. Launching a communication carrier is an opportunity that we have once in our lives. Crack open the current communication industry. Blow new wind into life. Why not create innovation with us? Why not do something big? Job Opening: Regular Employee Company Name Rakuten Mobile, Inc. Qualifications [Required] TOEIC score of 600 or equivalent English proficiency/skills. Rakuten Group Englishnization Rakuten Mobile, Inc. aims for all employees to achieve a TOEIC score of 800 or higher, in line with Rakuten Group, Inc.'s Englishnization policy. As a first step, a TOEIC score of 600 (or equivalent English proficiency) is required for mid-career hires. Job Responsibilities [Upon initial hiring] Varies depending on the position. The scope of work changes may include assignments to other duties determined by the company based on directives, etc. (If a transfer is ordered in accordance with the secondment regulations, the duties will be those of the seconded company.) Contract Period No fixed term Probationary Period Yes (3 months) The probationary period may be extended at the company's discretion. Employment conditions will not change during the probationary period. Work Location [Upon initial hiring] Headquarters (Rakuten Crimson House, 1-14-1 Tamagawa, Setagaya-ku, Tokyo), and other business sites. The scope of work location changes may include reassignments or transfers to locations nationwide and overseas. If remote work is partially permitted, the work location will be the remote work location approved by the company. The work location at the time of hiring will be communicated in the job description for each position and the offer letter. As a measure against passive smoking, smoking is prohibited on the premises of Rakuten Crimson House (however, this may vary depending on the business site). Working Hours Standard working hours: 9:00 AM - 5:30 PM On days when Rakuten Group morning meetings are held, the prescribed working hours will be 8:00 AM - 4:30 PM. Prescribed working hours are 7.5 hours, with a 1-hour break. A flextime system is partially applied. Core time: 11:00 AM - 3:00 PM (8:00 AM - 12:00 PM on morning meeting days) Some positions may differ from the above; details will be specified in the offer letter (e.g., application of discretionary labor system). Overtime work or work on holidays may be instructed. Holidays/Leave/Absence Complete two-day weekend system (Saturday and Sunday) and national holidays Summer vacation, New Year's holiday, annual paid leave, menstrual leave, special leave (condolence, volunteer, etc.) Maternity leave, childcare leave, family care leave Some positions may differ from the above; details will be specified in the offer letter. Salary Monthly salary: JPY300,000 ~ (Breakdown: Base salary JPY 227,848 + fixed overtime pay for 40 hours JPY 72,152) The above is the minimum salary offered for mid-career hires. Overtime work exceeding 40 hours per month will be paid separately as overtime allowance. Some positions may differ from the above; details will be specified in the offer letter (e.g., application of discretionary labor system). Commuting allowance will be provided (conditions and maximum amount apply). Salary Increase Yes Reviewed in January and July based on company performance and individual evaluation. Bonus Yes Paid in June and December based on company performance and individual evaluation. Stock Option Plan Yes Retirement Allowance Yes Insurance Employees' Pension Insurance, Health Insurance, Workers' Accident Compensation Insurance, Employment Insurance, etc. Benefits Cafeteria (breakfast, lunch, dinner generally free) Employee Stock Ownership Plan English learning support, etc. Job Opening: Fixed-term Employee Company Name Rakuten Mobile, Inc. Qualifications Varies depending on the recruiting position. Job Responsibilities [Upon initial hiring] Varies depending on the recruiting position. The scope of work changes may include assignments to other duties determined by the company based on directives, etc. (If a transfer is ordered in accordance with the secondment regulations, the duties will be those of the seconded company.) Contract Period Fixed term Maximum contract renewal period: Yes (The total contract period is 5 years, starting from the initial employment contract date.) Probationary Period None Work Location [Upon initial hiring] Headquarters (Rakuten Crimson House, 1-14-1 Tamagawa, Setagaya-ku, Tokyo), and other business sites. The scope of work location changes may include reassignments or transfers to locations nationwide and overseas. If remote work is partially permitted, the work location will be the remote work location approved by the company. The work location at the time of hiring will be communicated in the job description for each position and the offer letter. As a measure against passive smoking, smoking is prohibited on the premises of Rakuten Crimson House (however, this may vary depending on the business site). Working Hours Standard working hours: 9:00 AM - 5:30 PM On days when Rakuten Group morning meetings are held, the prescribed working hours will be 8:00 AM - 4:30 PM. Prescribed working hours are 7.5 hours, with a 1-hour break. A flextime system is partially applied. Core time: 11:00 AM - 3:00 PM (8:00 AM - 12:00 PM on morning meeting days) Some positions may differ from the above; details will be specified in the offer letter (e.g., application of discretionary labor system). Overtime work or work on holidays may be instructed. Holidays/Leave/Absence Complete two-day weekend system (Saturday and Sunday) and national holidays Summer vacation, New Year's holiday, annual paid leave, menstrual leave, special leave (condolence, volunteer, etc.) Maternity leave, childcare leave, family care leave Some positions may differ from the above; details will be specified in the offer letter. Salary Determined individually based on experience, etc. Commuting allowance will be provided (conditions and maximum amount apply). Salary Increase Yes Upon contract renewal, a salary revision may be proposed based on the most recent evaluation. Bonus May be paid taking into account company performance, general economic conditions, and work performance/abilities. Stock Option Plan None Retirement Allowance None Insurance Employees' Pension Insurance, Health Insurance, Workers' Accident Compensation Insurance, Employment Insurance, etc. Benefits Cafeteria (breakfast, lunch, dinner generally free) Employee Stock Ownership Plan English learning support, etc.

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