Mercoin: Mercari crypto trading, linked accounts, fees and cash exits

Mercoin puts crypto purchases inside Mercari’s Japanese shopping app. Users can buy from ¥1 using eligible balances and free promotional points, then monitor holdings without opening a separate trading application. The interface is designed around buying and selling a chosen yen amount. It is a retail dealer service rather than a conventional order-book terminal with maker and taker orders.[1][2]

Orders in Mercoin’s own disclosure are market orders expressed in whole yen, with a ¥1 minimum and a maximum that can vary by market or customer circumstances. Mercoin forms its quotes using cover-counterparty prices. The displayed quote must remain valid when accepted; stale or abnormal pricing can cause trading to pause.[2]

The trading FAQ gives the confirmation rate a five-second holding window. Once the purchase or sale is confirmed, the customer cannot cancel it or retrospectively change the amount. The product is spot ownership, and the FAQ does not describe leveraged borrowing or additional margin calls. Check the executable sell quote when deciding how much cash a disposal will produce.[24]

A chart price is the average of the platform’s buy and sell quotations. A holding’s displayed valuation therefore need not equal its immediately realisable sale value. This explains why a zero-commission purchase can show a lower sale value straight away: the spread remains an economic cost. Use the final buy and sell screens for a like-for-like price comparison.[24]

For example, moving ¥10,000 of available cash through a standard Merpay bank-withdrawal request leaves ¥9,800 after the ¥200 request fee. That illustration starts with cash already available in Merpay; it excludes any earlier trading spread or bank funding charge. Repeated small withdrawals incur the same fixed request charge each time.[12]

The SOL launch campaign offered 200 Mercari points for an eligible first purchase, but its published window ended on 14 September 2026. It is not a current October signup benefit. Campaign points also should not be presented as an unrestricted cash deposit: the announced reward was a unit usable within the Mercari group’s services.[4]

Funding and exit work around yen balances. Deposits can use Merpay or supported bank routes, while existing Merpay funds and eligible points can fund purchases without a separate advance deposit. External crypto deposits and withdrawals are unavailable. Consequently, this service cannot be used to receive coins from another exchange or send purchased coins to a personal blockchain wallet.[10]

The online-bank/ATM guide imposes no platform amount limit on that transfer route, although the sending bank can impose its own. Name mismatches prevent credit and require a return request through the sending institution. Eligible instant-payment transfers normally appear within minutes; transfers outside that bank’s supported hours can wait until the next business day. Maintenance and account restrictions can extend the delay.[13]

Standard bank payouts use a timetable with a 09:00 cutoff, not an immediate cash-out promise. A Monday application before 09:00 normally reaches a bank other than Japan Post on Tuesday; after that cutoff it is Wednesday. Japan Post takes an additional scheduled day in those examples. Holidays shift the timetable, while the separate Mercari Bank route to a registered Minna Bank account is generally immediate.[26]

Before treating the screen’s buying-power figure as withdrawable cash, check its components. Merpay funds, free points and deposited trading cash can all contribute to purchasing power. The amount that can be moved back to Merpay is shown separately in settings; it should be used for the cash-exit calculation.[11]

Mercoin’s disclosure says customer yen is held in a money trust with Rakuten Trust and customer crypto is segregated in cold wallets from company assets. The company manages the private keys. These arrangements explain where the customer balance sits; they do not turn the app balance into a self-custody wallet or a bank deposit with an assumed reimbursement limit.[2]

For assets purchased through the linked route, Coincheck is both the contractual trading counterparty and the company segregating the crypto. A Mercoin interface does not make Mercoin the custodian of those linked holdings. The accessible help disclosure is explicit on this distinction; its links to the fuller linked-account agreements returned errors during the review.[28]

The wallet-management policy describes controlled key handling, monitoring and incident escalation. A separate asset-return policy addresses failure to return crypto after events such as lost keys: Mercoin seeks to procure the same asset and quantity, but may use cash compensation when that is difficult, at a valuation method and date it determines. This is a contractual response policy, without a verified per-customer insurance limit.[21][22]

Passkey recovery can depend on the same Apple or Google account, another registered device, or an account-recovery procedure. A recovery screen may require My Number Card verification; users unable to complete that route are directed to further support. The guide gives no universal withdrawal-release clock following recovery, so restoring login should not be assumed to complete every security review immediately.[27]

Applicants must reside in Japan, complete identity verification and be aged eighteen to seventy-four when applying. A passkey is required and the service runs in the smartphone app, not a desktop or browser trading terminal. Turning seventy-five after opening triggers a purchase restriction, while sales and movement of available cash to Merpay remain possible.[8]

The application reuses eligible completed Mercari/Merpay verification, otherwise asking for the relevant identity information and documents. The Coincheck linked-account application can be preselected, with an opt-out checkbox. That application has its own review, and a person who already has an independently opened Coincheck account cannot open this linked account. Check the selected application before submitting.[9]

Stopping activity and closing the relationship are different actions. Mercoin’s closure guide says the crypto service cannot be closed by itself: full closure also requires leaving Mercari. To stop using it while retaining Mercari, sell the holdings, move the available cash out and disable recurring and point-purchase instructions. Closing the separate Coincheck linked account requires support, and that linked account cannot subsequently be reopened.[16]

Trading normally operates twenty-four hours a day, with unscheduled maintenance rather than a fixed weekly session. Maintenance can disable trading and cash-movement functions; Coincheck-linked assets can also have Coincheck-specific interruptions. The help centre says access from outside Japan can display a maintenance message. That message therefore does not always mean the entire domestic service is down.[14]

If a charge or trade is unfamiliar, inspect recurring-purchase settings and the dated history before reporting it. The incident guide asks for the affected account details, device, time and amount so support can trace the event. It does not authorise an enquiry message or telephone call as a replacement trading order during an outage.[15]

The FSA’s register dated 30 September 2026 lists 株式会社メルコイン as a cryptoasset exchange provider, Kanto Local Finance Bureau No. 00030, registered on 17 June 2022. This is an exact entity match for Mercoin. The registration is the relevant Japanese crypto-service status; it does not make every asset or return marketed inside the wider Mercari app a guaranteed investment.[7]

The linked service has a separate legal boundary: Mercoin mediates Coincheck retail spot transactions. Its help disclosure directs customers to Coincheck’s terms and linked-service provisions. Eligibility for Mercoin alone is therefore not approval for that second account, and Coincheck’s ordinary standalone exchange facilities should not be assumed to be available inside the linked interface.[28]

Mercoin, Inc. — 株式会社メルコイン — was established on 28 April 2021 and is part of the Mercari group. Its published company details identify a Tokyo head office and Keita Nakamura as representative. The consumer-facing service uses the Mercari brand and app, while Mercoin is the identified crypto operator.[6]

The June 2026 launch release reports more than four million cumulative crypto account openings by the end of March 2026, roughly three years after the service began. That is a dated company account total, not four million daily traders or verified funded accounts. The source provides no directly comparable daily exchange turnover. The figure nevertheless explains the service’s substantial domestic retail reach.[3]

Operator

株式会社メルコイン / Mercoin, Inc.

Exchange model

Centralised

Service scope

Retail crypto purchases inside the Mercari app, with a separate Coincheck connection.

Client types

Retail clients

Pricing publication

Public and quoted pricing

Pricing scope

No stated trade commission; executable quotations contain a spread.

Funding scope

JPY and eligible free points; cash exit through Merpay. External crypto transfers unavailable.

Custody and asset handling

Mercoin holds its customer crypto; linked purchases are held by Coincheck.

Client eligibility

Verified Japan residents aged 18–74 when applying.

Support

In-app enquiries and Japanese telephone support on weekdays.

Authorisation and registration scope

Japan cryptoasset exchange registration, Kanto No. 00030.

Exchange metadata checked 20 Oct 2026Source 1Source 2Source 5Source 6Source 7Source 8Source 10Source 19Source 23Source 28

Recurring purchases cover BTC, ETH and XRP, with a published setting range of ¥1–¥1,000,000 per asset. Customers can choose daily execution or one, two or four monthly purchases using the stated dates. An insufficient available balance can trigger a bank top-up; amounts below ¥1,000 trigger a ¥1,000 top-up. Several asset schedules can cause more than one bank charge.[18]

A new schedule starts on the first selected date after the setup day, with the selected funding bank shown before confirmation. Changes and cancellation require authentication. Cancelling on an execution day can be too late to stop that purchase, and completed recurring trades cannot be reversed. When several bank accounts are registered, the selected account in Merpay’s bank-management settings determines the debit source.[30]

The monthly ETH benefit is awarded as Mercari points, not additional ETH units. It uses the monthly average yen value of holdings and a variable displayed annual rate; points are normally issued by the sixth business day of the next month and expire after 180 days. Mercoin stakes part of its ETH. If heavy sales require unstaking, execution can take longer or trading can pause.[19]

Point investment is a separate automatic instruction: newly issued eligible free points buy BTC, ETH or both. When both are selected the allocation is equal, with an odd remaining point assigned to BTC. Disabling an asset stops future automatic buying; it does not sell existing holdings. This is a rule chosen by the customer, not an AI portfolio manager or authority for another trader to direct the account.[20]

Monthly CSV reports contain transactions and month-end balances, including linked-account reports. They remain available even in months without trades. After closure, the closure-month and following-month reports are provided; older missing copies require a support request. Download the available history before leaving so later accounting does not depend entirely on a new support interaction.[17]

The platform’s tax FAQ points customers to their transaction reports for annual profit calculations. It also explains that spending BTC on a Mercari purchase involves selling BTC at payment, which can create a disposal record. A chart’s unrealised gain is not a completed tax return; preserve the transaction CSV and the relevant purchase and sale history.[29]

Charts start on a weekly view. The last selected period persists when the trading screen is reopened without closing the app, and individual asset charts refresh their latest price every ten seconds. This documented local behaviour is narrower than cross-device layout synchronisation. The combined holdings chart does not have that automatic refresh, so use an individual asset screen when following its current movement.[25]