Note: This article covers Merpay, a mobile payment service available only to merchants and customers in Japan. The information below will not be relevant if you are not selling in the Japanese market.
Merpay is a mobile payment service offered by Mercari, Japan's largest flea-market app. This article explains the pros and cons of adding Merpay to your Shopify store, along with the specific steps to set it up. With 18.73 million users, adopting Merpay could help boost your e-commerce sales.
What Is Merpay?
Source: Merpay official site
Merpay is a mobile payment service offered by Mercari, Japan's most-used flea-market app. According to the Q2 FY2025 (ending June 2025) Data Sheet, Merpay has 18.73 million users (17.41 million of whom are identity-verified).
Benefits of Adding Merpay to Shopify
(For customers) Less hassle entering credit card details
Merpay lets shoppers pay smoothly through the Mercari app. With credit card payments, customers have to enter their card number, expiration date, security code, and so on — with Merpay, none of that data entry is needed.
(For customers) Mercari sales proceeds and points can be used for payment
Users can apply proceeds and points they've earned from selling on Mercari directly toward Merpay payments.
(For stores) Potential for new customer acquisition
Adding Merpay to your Shopify store lets you tap into roughly 22.79 million monthly Mercari users (reference: Q2 FY2025 (ending June 2025) Data Sheet) as a potential customer base.
(For stores) Helps reduce cart abandonment
Source: Baymard Institute
According to a Baymard Institute survey, the 4th most common reason for cart abandonment is "didn't want to enter credit card information," and the 10th most common is "not enough payment options." The majority of cart abandonment stems from the reason "the payment method I want isn't available." Adding Merpay is worth considering to help prevent cart abandonment among customers who don't own — or prefer not to use — a credit card.
The blog article below introduces other reasons for cart abandonment as well as countermeasures beyond simply adding more payment options. Please use it as a reference.
Drawbacks of Adding Merpay to Shopify
It comes with a cost
The main drawback of using Merpay is that it comes with additional costs.
Using Merpay may add setup fees, monthly fees, and payment processing fees. Because Merpay is a payment method outside Shopify Payments, it also incurs a transaction fee (📍).
High fees eat into your store's profit margin, so if you want to keep costs down, choose a provider with lower fees.
The blog article below explains in detail the benefits of using Shopify Payments and its payment fees. Please use it as a reference.
📍 What is a transaction fee?
A transaction fee is a fee charged when you receive payment from a customer.
When you use a payment method from an external provider other than Shopify Payments, a fee is charged equal to the payment amount multiplied by the following rate.
| Plan Name | Starter | Basic | Standard | Premium | Plus |
|---|---|---|---|---|---|
| Transaction Fee | 5% | 2% | 1% | 0.50% | 0.15% |
The blog article below thoroughly compares Shopify plans across various criteria besides transaction fees, such as monthly cost and staff account limits. Please use it as a reference.
Recommended Payment Provider for Adding Merpay
KOMOJU
To add Merpay to Shopify, we recommend contracting with KOMOJU. KOMOJU is known for having no setup fee or monthly fee, and for its fast screening process.
Merpay Fees
| Setup Fee | Monthly Fee | Payment Fee |
|---|---|---|
| ¥0 | ¥0 | Physical goods 3.5% Digital content 9% |
Reference: https://ja.komoju.com/payment-methods/japan/merpay/
A Shopify App That Can Automatically Hide Merpay
After adding Merpay, you may run into situations where you want to hide it — for example, "digital products have high fees, so I want to hide Merpay for those."
This section introduces a Shopify app that can hide Merpay under any condition.
RuffRuff Order Limits
RuffRuff Order Limits is fully localized for Japanese and is Japan's first Shopify app built on the Cart and Checkout Validation API.
By using the Cart and Checkout Validation API, it handles order-restriction logic on the server side — processing that previously could only be done on the front end. As a result, it achieves more robust order restrictions that are harder to bypass compared to existing order-limit apps.
With a single app, you can apply quantity limits, amount limits, bundling restrictions, customer restrictions, and payment method hiding.
Using this app, you can achieve things such as:
・Hide Merpay when the cart subtotal reaches ¥3,000 or more
・Hide Merpay when the cart contains digital products
・Hide Merpay for guest customers only
The blog article below explains how to use RuffRuff Order Limits to automatically hide mobile (QR code) payment methods, including Merpay, when the subtotal exceeds ¥50,000. Please use it as a reference.
Summary
Merpay is a convenient payment method for customers who don't use credit cards, as well as those who want to use their Mercari sales proceeds and points. In particular, it's expected to help address cart abandonment caused by "the payment method I want isn't available." On the other hand, it comes with costs such as setup fees, monthly fees, and transaction fees, so careful consideration aligned with your store's profit margins and operating policy is needed.
When adding Merpay to Shopify, using a payment provider such as KOMOJU can reduce the burden of setup fees and screening. There are also ways to hide Merpay for specific products, such as digital goods, allowing for flexible operation.
Whether to adopt Merpay should be decided based on your store's target audience and sales strategy. Compare it against other payment methods and weigh the costs to choose the best payment option for your store.
Finally, the blog article below introduces other payment methods you can add to Shopify besides Merpay. If you're considering adding a new payment method, please use it as a reference.
