Security Engineer

This position belongs to DeNA’s security technology group, which is responsible for security across the DeNA Group. The group is an engineering organization centered on conducting vulnerability assessments in-house. Its wider scope includes network assessments, product and system development, SOC activities, and technical support for internal security-control activities. The role is part of the central security function and provides technical support so business divisions can reduce security risks and strengthen their countermeasures.

The main work includes conducting and reporting vulnerability assessments of web applications, mobile applications, and games at the request of business divisions. The engineer also collects and evaluates vulnerability disclosures and security-threat information published worldwide, communicates relevant information internally, and promotes appropriate responses. When an internal incident or a similar event occurs, the role provides technical investigation and response support.

The position contributes to the broader work of the security technology group according to the engineer’s strengths, including SOC activities, network assessments, and security-control activities. It also involves developing and operating products, tools, and systems to improve the efficiency and sophistication of security operations. Research into AI-enabled assessment and defense methods, followed by practical application, is part of the role. The team has begun work on automating and advancing assessment and defense through AI agents, with the possibility of developing these capabilities as internally built products. LLM and agent technologies are specifically considered in the security context.

The posting seeks a security engineer with extensive practical experience. The team includes many junior members, and experienced members are expected to provide technical mentoring and code reviews, as well as set a professional standard through their approach to work and professional conduct. The posting does not state a formal education requirement or a specific number of years of experience.

The listed work locations are DeNA’s Shibuya office in Tokyo, Yokohama Arai Building office, or Yokohama BASEGATE office, with remote work possible from home or another location approved by the company. The work-location range may change to company-designated workplaces, including remote-work locations. The listed office environments are indoors non-smoking, with designated indoor smoking areas available.