Job Description: About Organization Security Engineering & Operations Department supports Rakuten Mobile and related services by providing robust security infrastructure, network security, identity/access management, and security operations platforms. As our business scales, ensuring secure and reliable operations across on-premises, cloud, and Kubernetes environments is mission-critical. To support Rakuten Mobile’s rapid growth, we are continuously expanding our Linux/Kubernetes-based platforms and enhancing our authentication and secrets management capabilities. We are seeking an experienced engineer with 8+ years of hands-on expertise to accelerate stable operations, drive standardization, and elevate the security quality of our mission-critical infrastructure. The Network Security Engineering Section designs and operates secure network services using an advanced technology stack including Linux, RHEL, Kubernetes, IPA/FreeIPA, and Vault. Job Duties Linux Infrastructure: Design, build, operate, and troubleshoot Red Hat Enterprise Linux and diverse Linux environments. Kubernetes Security: Securely operate, configure, and optimize Kubernetes clusters and related components to meet growing operational demands. Identity & Access Management: Manage authentication, user lifecycle, authorization, and policies using IPA/FreeIPA. Secrets & Certificate Management: Design and operate secrets management, PKI/certificate management, and access control using HashiCorp Vault or equivalent tools. Security Hardening: Perform security hardening, patch management, and audit support for Linux/Kubernetes environments to ensure high security standards. Automation: Drive configuration management, automation, and standardization using tools such as Ansible to improve operational efficiency. Incident Management: Handle incidents, conduct root-cause analysis (RCA), and implement preventive measures for mission-critical services. Cross-functional Collaboration: Work closely with network, cloud, security, and operations teams, utilizing English for technical communication and project coordination in a global environment. Minimum Qualifications 8+ years of hands-on experience designing, building, and operating Linux/RHEL environments. Proven experience in operating, configuring, and troubleshooting Kubernetes environments. Practical experience with authentication platforms (IPA/FreeIPA), including user and authorization management. Practical experience with secrets management, certificate management, and access control (Vault or equivalent). Strong background in Linux security hardening, patch management, and vulnerability remediation. Fundamental knowledge of networking, DNS, TLS/PKI, firewalls, and load balancers. Strong analytical skills to independently handle incidents, analyze root causes, and improve operational processes. Professional proficiency in English (technical documentation, communication, and collaboration). Preferred Qualifications Experience operating large-scale telecommunications, cloud, or mission-critical infrastructure. Automation experience using Ansible, Terraform, Python, or Shell scripting. Deep knowledge of Kubernetes security (RBAC, NetworkPolicy, container image management). Experience with monitoring, log analysis, SIEM integration, and incident response workflows. Relevant certifications such as RHCE, CKA, CKS, or other security-related credentials. Experience driving projects within global teams and managing multiple stakeholders. Work Environment Department: Network Security Engineering Section, Security Engineering Department. Collaboration: Work alongside global teams with diverse backgrounds in Linux, networking, security, cloud, and Kubernetes. Stack: RHEL, Kubernetes, IPA/FreeIPA, Vault, Ansible, Git, CI/CD, and various monitoring/logging tools across on-premises and cloud environments. 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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