Job Description: Backend Engineer / LINE Platform

Position Outline

As a Backend Engineer, you will be responsible for the backend systems powering the "LINE" app, which processes tens of billions of messages per day. The role includes ensuring the safety and reliability of this critical infrastructure while evolving it to meet diverse and growing user and business needs.

You will focus on developing, improving, and operating large-scale backend systems that sustain significant traffic efficiently, as well as supporting the backend through which LY Corporation brings new value to users.

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Organization’s Mission and Goals

• Reliability & Security: Achieve reliability and information protection at a societal-infrastructure level while maintaining innovation speed.
• Scalability & Flexibility: Realize expandability to adapt to diverse and changing needs across countries and cultures.
• Innovation: Fuse stable foundations with intelligent applications to create breakthroughs in communication.

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Job Details

You will be responsible for the design, development, testing, and post-release operation of messaging for the LINE app and Official Account backend system. Specific responsibilities include:

• Design and development of server-side functions and APIs related to LINE's messaging, social graph, and family services.
• Design and development of large-scale data structures optimized for distributed processing and scalability.
• Continuous improvement of the structure, performance, and scalability of LINE’s foundational platform, and creating a technical vision to flexibly meet diverse business requirements.

Note: You may be reassigned to other duties as determined by the company.

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Product Overview

• LINE: Communication app for messaging, voice, and video calls connecting people, information, and services.
• LINE Official Account: Platform for businesses to communicate with users seamlessly via LINE.
• LYP Premium: Monthly membership service offering exclusive benefits and services.

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Ideal Candidate

• Interested in complex, large-scale distributed systems and their challenges.
• Takes initiative, collaborates with others, and assumes responsibility.
• Able to work positively and cooperatively within a diverse team.
• A quick learner who can efficiently find and execute realistic solutions to meet team goals.

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Required Experience & Skills

• 3+ years of server-side development experience (JVM languages or C/C++).
• Experience operating production systems in Linux/Unix environments.
• Experience with databases such as MySQL, Redis, HBase, Cassandra, Elasticsearch, etc.

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Preferred Experience & Skills

• Experience designing/developing server applications and databases in high-traffic environments.
• Knowledge of JVM tuning and monitoring.
• College/graduate major in Computer Science or related field.
• Business-level English (reading/writing); either Business English or Business Japanese (speaking).

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Development Environment

• Languages/Frameworks: Java, Kotlin, Scala, Spring Framework
• Observability: Prometheus, Grafana, AlertManager, Elasticsearch, Kibana, Zipkin
• Databases/Storage: Redis, Apache HBase, Apache Kafka, MongoDB
• Infrastructure: Containers (Kubernetes), VM/PM on Private Cloud
• DevOps: Ansible, ArgoCD, Jenkins, GitHub Actions

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Salary

• Expected Annual Salary: JPY 7,000,000 – JPY 18,000,000
• Salary Form: Monthly (includes fixed overtime allowance)
• Standard Monthly Salary: JPY 467,000 – JPY 1,200,000
  • Base Salary: JPY 361,000 – JPY 934,000
  • Fixed Overtime Allowance (35 hours): JPY 105,000 – JPY 267,000
• Bonuses: Up to 2x/year (amount depends on company/department performance)
• Allowances: Overtime allowance, commuting allowance (up to JPY 150,000/month), remote work allowance (JPY 11,000/month)

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Employment Type

• Type: Permanent employee (no fixed term)

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Work Location

• Office in Kioicho, Chiyoda-ku, Tokyo
• Wheelchair accessible
• Mainly non-smoking environment (with designated smoking rooms)

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Work Hours

• Flextime system: Standard 7 hours 45 minutes per day (no core hours)
  • Standard company hours: 9:30 a.m. – 6:15 p.m.
  • Shortened work hours available for childcare/caregiving

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Holidays & Leave

• Days off: 2/week (Saturday & Sunday), national holidays, New Year's holiday
• Leave: Paid leave, special paid leave (condolence, maternity, sick childcare, nursing care, etc.), "Happy Friday", sabbatical leave

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Benefits

• Comprehensive social insurance (health, nursing care, pension, employment, workers' compensation)
• Optional DC Pension Plan
• Group Insurance (Welfare, Long-term Disability)
• Employee savings/cumulative stock plans
• Health subsidies (e.g., re-examination after checkup)
• In-house massage room, club activities, social event subsidies

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Talent Development / Support Systems

• Training programs, language courses, management training
• Sabbatical leave, doctoral studies support program, and more

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Selection Process

1. Application
2. Coding Test/Assignment
3. Interviews / Background Check
4. Offer

Technical Evaluation:

• Pre-interview web coding test (up to 3 hours)
• Live coding interview
• Whiteboard discussion interview

Soft Skills & Cultural Fit:

• Interviews/discussions with team members

The entire process typically takes 4–6 weeks. All applicants will be notified of results via email.

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**End of Job Description**