Senior Frontend Engineer
- Tokyo
- Partial Remote
- Full-time
- August 28, 2025
This is a full-time position for a Senior Frontend Engineer for in-house software developmen,t aiming to revolutionize the market for used electronic devices. The engineer has a passion for startups and is also able to take part of the materials on our Company page. We employ a remote/offline hybrid work style, enabling more flexibility, thus requiring candidates to be located in the Metropolitan Tokyo Area.
About Belong
Belong is building an ecosystem for used mobile devices based on the mission of "delivering the next level of value that our loved ones can be proud of." with an international mindset and successfully employing cutting edge software development skills with a keen eye for quality in an otherwise cost-intensive competitive industry.
Being different is our strength
Founded as a result of an internal effort at Itochu, we're not your typical startup. Our team members come from diverse backgrounds such as Japan, USA, Bangladesh, Sweden and Germany, and as we grow it, diversity is something we strive to increase, as having a wide variety of perspectives makes us stronger. Many of our members have an international background from all over the world, but we keep our business language to Japanese.
This variety in perspectives is what enabled us to see the possible solutions to the process optimization issues we’re currently employing to the refurbished used electronics industry, and our backgrounds helped us approach the issues with a wider range of not only tools but also a wider range of options of how to solve the issues.
We're a stable startup, which fights with quality and process in mind, always aiming for creating a more efficient, qualitative product for which we’re already receiving high praises domestically and internationally.
This we've been doing successfully for five years and have just established ourselves in New York, USA - creating the need for an even more international and challenge driven team.
On top of that we’re also pushing the boundaries of our business by incorporating more and more AI trendy concepts such as LLM and Agents. We like to stay busy learning and adapting.
We got a factory
Unlike many other startups, we’ve got a factory that is the heart of our business model. There we receive electronics that are to be refurbished and released back onto the market. Optimizing the process for grading the devices, refurbishing, re-selling - all aspects improve our cost performance ratio enabling us to polish the units even more thus improving the quality of the end product. This is how we fight, in a market normally considered a red ocean and focused on driving prices down.
Our business is unique, and our approach to technology strengthens our case. Our CTO, Fukui Tatsuya, also says that it's important for us to share our know-how with the rest of Japan who are trying to make something truly unique, providing concrete sustainable value to their end-users. For this effort, he’s been a present part of the startup and AI scene in Japan, always striving for others to achieve more by contributing his rare perspective.
In our Factory-centric approach, we've been working with several different products in various stages since the start, doing everything from smartphone app development, E-commerce to IoT. From 2023 we're also incorporating areas such as AI & Machine Learning.
This we execute by having several dedicated agile teams which are working closely together with our operation and business teams with the aim of not only creating product value but also enabling our company to incorporate a firm engineering perspective to our business model.
About the position
As a Software Engineer (Frontend), you'll build our web apps together with our UX/UI Designer to bridge the gap between graphical design and technical implementation, taking a leading role on both how applications look as well as work - creating apps together with our users that solve their needs with a touch of joy.
The web applications you build will have clean code and reusable components, with automated tests to accompany them. They'll be optimized for performance and scalability. We believe that you have mastered the intricacies of React and CSS Components, believe that managing your own webpack configurations is a waste of time, know the value of testing with Jest and want to leave a thorough footprint on what you are building. Perhaps you've also delved with E-commerce solutions such as Shopify?
This position is mainly for the teams for Nicosuma and Nicosuma Kaitori, Belong's services for individual customers.
Your position will entail tasks such as
- Grooming, planning, estimating user stories & features with PM, PO and the rest of the team
- Making architectural decisions together with the team
- Coding, lots of coding
- Planning and implementing testing strategies
- Helping out with recruiting, onboarding and training new members
- Pushing the team to achieve even more by forming, evaluating and implementing new processes and policies
- Responding to incidents together with the team as a part of the on-call effort
As this position will be for an experienced member of our team, we ask that you fulfill the following requirements:
- Native proficiency in Japanese, or at least JLPT N2
- Do note that the less proficient you are in Japanese we will require you to compensate with higher technical capabilities.
- At least 5 years of experience related to the position. (If the university is in the field of telecommunication, information technology or computer science, the above experience would be sufficient; otherwise, an additional year would be required.)
- Experience with React.js & Next.js
- Experience with Typescript
- Experience with Git
- Experience with working in a fully digital environment(chat communication, online task boards etc)
- Experience with utilizing technologies such as ChatGPT, Gemini or similar for information gathering and work optimization (creating documentation etc) and Coding Agents for coding support
- Able to commute to the office and work on-site.
We would also like to see experience with any of the following:
- Development methodologies such as TDD, SOLID or SCRUM
- Experience with working as a part of a larger development team
- Experience utilizing SCSS, CSS Components, Sass or styled-components (if web)
- Has been involved in the performance & delivery optimization of web apps
- Utilizing new protocols such as GraphQL, HTTP/3, gRPC or QUIC for communicating with servers
- Building modern server rendered application with frameworks such as Next.js
- Experience with leading, or assisting in leading, a team effort
- Experience with working tightly with end-user and mapping complex user journeys
- Experience with modeling & maintaining non-trivial data models
- Experience with developing and maintaining Warehouse Management Systems
- Experience with implementing Core Web Fundamentals or other concepts relevant to Web Performance
- Experience in evaluating and implementing strategies for improving SEO
- Experience with Figma
- Experience with Jest, vitest, Cypress
- Business level proficiency in English (TOEIC 800, CAE C+ or similar)
What we can offer
- Flexibility: A hybrid work style, enabling remote and offline work, and flexible work hours, with core time between 10:00-15:00, with the principle of "Frihet under ansvar" (Freedom with responsibility). For more senior Engineers, we ask them to come to the office at least 3 times per week for team building and synchronization purposes.
- Ample of understanding for young parents: Many of us have children, and want to passionately pursue a fulfilling career - our workplace makes it easy to take care of sick children at home or manage topics at school or kindergarten
- Impact: The opportunity to make a positive impact on society by contributing to meaningful work that benefits people.
- Compensation: Market-level salaries with a performance-based bonus system.
- Stability: As a subsidiary of Itochu, with stable revenue points since founding, we’re stable to the extent where we haven’t had to compromise with bonus payments up to this point
We believe in a Swedish saying - "Frihet under ansvar" which roughly translates to "Freedom comes with responsibility". Take ownership of your responsibilities and what you build, then you can adjust your work hours flexibly and also choose where to spend them - like working while traveling.
The work we do has the chance to make a positive impact on society, something that will actually matter to people - and we believe that this is something that is important for you just as much as it is for us.
We offer market level salaries complemented with a performance based bonus system, accompanied with the ability to leave a footprint on society making tomorrow into something better than what we have today.
About Belong
Belong specializes in the reuse market, primarily focusing on used mobile devices such as smartphones and tablets.
As a wholly-owned subsidiary of the globally renowned ITOCHU Corporation, Belong leverages the ITOCHU Group's extensive domestic and international procurement and sales channels, as well as other resources. Despite being a late entrant to the market, Belong has established world-class operations and provides high-quality devices by implementing a proprietary inspection process that is continuously improved.
Furthermore, these initiatives and achievements have been recognized by leading companies, leading to collaborations with various enterprises.
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