Senior Full-stack Software Engineer

Lunaris Musashino-shi, Tokyo November 10 2026
  • 💴 ¥6M ~ ¥8M annually
  • 🏢
    No remote
  • 🗾 Japan residents only
  • 💬
    No Japanese required
    Business English
  • 🧪
    Senior level
    5+ years experience required
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About Lunaris

Lunaris Musashino-shi, Tokyo

We started out as an otaku-centric online shop called Solaris Japan, and now offer solutions to other e-commerce platforms. We're small enough to where your ideas and work can have a huge impact but self-funded, and mature enough to be stable.

Key benefits

  • Self-funded and stable
  • Free weekly Japanese lessons
  • Free weekly massage

About the position

Lunaris is looking for a Senior Full-stack Software Engineer to join the development team of our Japanese learning app that combines language learning with some video game mechanics wrapped in beautiful pixel art visuals.

In this role, you’ll help bring the project to release by developing gameplay systems, implementing new features, influencing the direction, and ensuring a smooth and engaging experience for players. You’ll work closely with the creative team to turn ideas into reality.

Development is already underway, with most key features implemented. We’re looking for someone comfortable familiarizing themselves with pre-existing systems and identifying opportunities to improve them as development progresses.

We are a small, self-funded company with around 10 members on our engineering team, working on several projects. You’ll have an opportunity to make a real impact on the project and grow as an engineer. As such, we are looking for someone who has excellent technical knowledge and skills while also taking initiative and challenging themselves by tackling complex problems with confidence and care.

Responsibilities

  • Get familiar with the existing codebase, understand previously implemented features and technical decisions
  • Regularly document and test modules and functions
  • Be able to work independently and see projects through from conception to completion
  • Proactively collaborate with team members to complete tasks and projects
  • Participate in code reviews and adhere to coding standards and best practices

Requirements

  • At least 5 years of experience as a software engineer
  • Strong understanding of data structures, algorithms and system design
  • Interest in video games and Japanese language learning
  • Highly motivated and independent
  • Strong communication and teamwork abilities

Nice to haves

While not specifically required, tell us if you have any of the following.

  • Educational or game-related applications
  • React Native, React, or other mobile application development frameworks
  • Expo for building and deploying mobile applications
  • Elixir and commonly used packages in its ecosystem, such as Oban, Oban Pro, Broadway, and more
  • Implementing multiplayer features or real-time communication systems

Compensation

¥6,000,000 ~ ¥8,000,000 annually.

Includes bonuses, paid out twice per year.

Hiring Process

  1. 1

    Online Interview with Founder and Senior Engineer(s) - 60min

    We’ll discuss your engineering background and past experience, and give you a chance to learn more about our company.

  2. 2

    Technical assignment

    You’ll have a chance to show off your technical skills by completing a small assignment. You have some freedom in what language(s) and technologies you use to complete this assignment, so don’t sweat it if you’ve never used Elixir before!

  3. 3

    In-person or remote interview with the team - 90-120min

    If you’re currently based in Tokyo, you’ll have an opportunity to enjoy lunch or dinner (on us!) at our office in Kichijoji. If you’re based outside of Tokyo, we’ll have a group video call. Either way, this will be a chance to meet and talk with members from various teams at our company. After that, there will be a technical interview with our engineers where you’ll discuss your solution to the above technical assignment as well as discuss other technical topics.

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DO YOU NEED MORE INFO?
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