“For anything you don't understand, turn to System I.”
From mobile app development to backend systems, a valuable partner you can entrust with everything.
REXEV Co., Ltd., which was seeking a partner for the development of a mobile app for an EV car-sharing system.
Following our company's app update, we have continued to entrust System Eye with development work. This time, we spoke with Manager Fumiyuki Moriya about why System Eye was chosen and the benefits revealed through our collaboration.
Issues Prior to Support
・Rapid updates for mobile apps
・Finding development partners with mobile app skills and knowledge
Effects of Your Support
・Completed the entire process from handover to release within a short one-month period
・Established an environment enabling focus on core business operations by having a reliable development partner
Table of Contents
We were looking for a development partner who could streamline the development of a car-sharing app.
“When you're stuck with app development, System Eye is the one to turn to.” Now a trusted partner.
With System Eye, you can entrust us with everything from app development to backend systems.
REXEV Co., Ltd.
REXEV Co., Ltd. is a company engaged in the introduction, operation support, and consulting services for e-mobility, primarily focused on electric vehicles (EVs).
We operate the EV car-sharing service “eemo” and develop and provide systems for corporations introducing EV car-sharing. We are working in partnership with local governments and corporations to promote the adoption of e-mobility that maximizes the use of renewable energy.
REXEV Co., Ltd. Official Website
We were looking for a development partner who could streamline the development of a car-sharing app.
－Please provide an overview of the services and systems that were the subject of development.
The first development project we were commissioned for was modifying the “eemo” app for an EV car-sharing service.
The “eemo” service we provide specializes in electric vehicle car-sharing. We launched in the Odawara/Hakone area, establishing a sustainable cycle where vehicles run on locally generated renewable energy.
“eemo” employs a system where everything from pre-registration to same-day usage is completed via a smartphone app. By photographing and registering your driver's license upon joining, you can easily reserve vehicles directly from the app.
Furthermore, by packaging the “eemo” business model, we also provide implementation support for businesses wishing to start electric vehicle car sharing. Concurrently, we are expanding our system development and provision services. System Eye is currently responsible for developing apps tailored to the specific services each business operator launches.
－Please tell us the purpose and background behind your decision to outsource app development.
The primary objective is to streamline system development, including app development.
Our company operates multiple businesses, including energy-related services utilizing EVs, making the optimal allocation of internal resources a critical theme. Therefore, our in-house engineers intended to focus their efforts on developing management systems. App development for the car-sharing business requires a flexible development structure, as each project has distinct characteristics. We believed outsourcing these tasks would allow for more effective use of internal resources, and had previously outsourced them to an external development partner.
However, that development partner was acquired, making it difficult to place orders. This led to the need to find a new partner to collaborate with on development.
Furthermore, around that time, Google Play Store regulations were tightened. Apps requiring access to users' photo folders needed updates to comply with these stricter regulations. Our app, “eemo,” was also affected, making the search for a development partner urgent. Anticipating future additional development needs, we formally began the process of selecting a development partner.
Both the proposal content and the estimate demonstrated a high level of expertise in mobile app development.
－Please tell us how you came to know System Eye during the process of selecting a development partner.
The initial contact came through an introduction from one of our in-house engineers. They had previously worked with System Eye on a different project and apparently remembered their work quality favorably.
At the time, we were comparing several development partners. System Eye was highly regarded internally for their “quick response times” and “commitment to seeing projects through to completion,” and they enjoyed particularly strong support from our engineers. This led to our decision to engage them.
－What were the key factors that led you to choose System I?
One key factor in choosing System Eye was the responsiveness demonstrated in their proposals and other communications. Many other vendors we considered either responded slowly to inquiries or expressed reluctance to take on a project involving switching development partners. In contrast, System Eye's responses were overwhelmingly faster than other vendors, enabling smooth communication and making collaboration feel effortless.
Their proposal was also clear in defining the scope (project boundaries, tasks, deliverables) and demonstrated a solid grasp of our company's objectives.
From System Eye's perspective, taking over a system partially built by another development partner and redeveloping it must have been a laborious task. Despite this, we sensed their willingness to adapt flexibly, which gave us confidence to entrust them with the project.
Another reason was that the costs stayed within our budget. While many vendors provided estimates that seemed inflated at first glance, System Eye thoroughly understood our requirements and presented a reasonable price. This also demonstrated that they have engineers with expertise in mobile app development.
Furthermore, we had previously heard that System Eye's CTO expressed interest in the REXEV business sector, including electric vehicles. The idea that a vendor favorable to our business could potentially become a long-term partner for future development projects also contributed to our decision to engage them.
“When you're stuck with app development, System Eye is the place to go.” Now a trusted resource.
－Did the progress of the initial app modification project you requested go smoothly?
The eemo app modification project proceeded smoothly despite the tight deadline. Addressing Google Play Store's stricter regulations had a fixed deadline, and failure to comply risked removal from the app store. This posed a risk to new customer acquisition, making the approximately one-month deadline extremely tight. Nevertheless, the delivery was completed without any issues.
We are currently also requesting System Eye to develop an app for EV car-sharing operators. We recognize this is a challenging request, as it involves multiple departments requiring separate budgets and estimates, and the requirements tend to become complex. We appreciate their flexible approach.
－Have you achieved any results through app development with System Eye?
From the perspective of streamlining app development, finding a partner who responds promptly and adapts flexibly has been a major achievement, especially given the necessity of collaborating with external development partners. In fact, we've requested estimates with every specification change, and they've always willingly accommodated us each time.
Additionally, we appreciate your flexible approach, such as consolidating multiple release dates for us. System Eye has impressed us with its high level of expertise in app development—so much so that we initially thought you were a vendor specializing solely in app development. Having a reliable partner we can turn to when we encounter challenges internally, thinking “Let's ask System Eye,” is truly reassuring.
With System Eye, you can entrust us with everything from app development to backend systems.
－Please tell us what makes System I attractive as a development partner.
Their flexibility to handle everything from simple revision requests to complex development, coupled with their broad range of skills and knowledge, is truly appealing.
I particularly value their comprehensive capability to handle everything from apps to backend systems. They are a valuable resource that eliminates the need to switch development partners for each project, significantly improving operational efficiency when placing orders. Moving forward, I hope they will leverage their expertise to propose fresh perspectives even within existing frameworks.
Their quick response times are also a major plus. Especially in projects involving many stakeholders, slow responses make smooth progress difficult. System Eye responds swiftly to estimates and discussion points, allowing us to move forward almost without a hitch—something we're very satisfied with.
－Please share your future outlook.
System Eye possesses expertise in areas where our company lacks in-depth knowledge. Therefore, we are considering moving beyond spot orders to establish a long-term contract that helps reduce man-hours while also allowing us to receive timely advice. As the need for streamlining system development grows, strengthening our collaboration will become essential.
Currently, you handle one-off app development and modifications. We place our trust in System Eye's solid approach, evident in meticulously creating test cases even for minor changes. Moving forward, we hope you will become a long-term partner who comprehensively supports our business systems—handling new feature development from requirements definition and entrusting us with bug investigations.
Company Name : REXEV Co., Ltd.
Address : Tokyo
Business Type : EV Car Sharing Business
Scale : 22 members (as of July 2025)
