Quick-deposit 4-method decomposition framework

Wiki route

This entry sits under banking index. Read it against Regional bank consolidation pattern for peer / contrast context and Cooperative banking in Japan for the broader system / regulatory boundary.

[!info] TL;DR “What determines the instant-deposit UX is the underlying bank-connection method.”

Core thesis

Japan’s instant deposit (quick deposit) looks similar on the surface, but can be decomposed into 4 methods whose contractual premises, authentication burden, and liability boundaries are entirely different. This classification is essential for diagnosing the current state of adopting firms and proposing UX improvements.

Comparison of the 4 methods

Method	Contractual premise	Initial auth	Per-transaction auth	UX burden	Representative case
1. Bank-login type	Operator × bank (not a collection institution)	None	Login + OTP every time	High	Rakuten Securities, SBI Net Bank
2. Account-linkage type (OAuth)	Operator × bank (EPSP registration required)	OAuth consent	Not needed	Minimal	Daiwa Connect Securities × Minna Bank, Merpay × Sumishin SBI, Revolut × Minna Bank
3. Pay-easy/MPN type	Operator × collection-institution number	None	Login + 3 number every time	High	Coincheck, GMO Coin, SBI VC Trade
4. Payment-gateway-routed type	Operator × payment gateway × bank	None	Login every time	Medium	GMO-PG “PG Multi Payment Service”

Points for method selection

From the operator’s perspective

Structural reduction of authentication burden → Method 2 (OAuth) is almost the only choice
Lightness of initial investment → Method 3 (Pay-easy) is low (no EPSP registration needed)
Avoiding dependence on payment gateways → Method 1 or 2 (Method 4 depends on an intermediary)
A formal relationship to capture account share → Method 2 (the OAuth token is the implementation of a continuing relationship)

From the user’s perspective

Authenticate only the first time, then one-tap thereafter → Method 2 only
Trust in the bank brand → Also assured by Method 1 / 3
Transparency of statements → Recorded on the bank-side statement under any method

By-product: Pay-easy 7-day transfer restriction

Many crypto-asset operators using Method 3 (Pay-easy) restrict external transfers for 7 days after deposit (anti-money-laundering measure). Switching to Method 2 (OAuth) can, in some cases, ease this restriction. A large UX differentiator.

Meaning of Electronic Payment Service Provider registration

Newly established in the 2017 年 Banking Act amendment
When fully offering Method 2 (account-linkage type), the operator normally needs EPSP registration
Methods 1 / 3 / 4 can be operated without EPSP registration (relying on the bank’s net banking)
EPSP registration = the de-facto threshold for “operator qualification to invoke the bank API’s write/update endpoints”

Read APIs vs Write APIs

Category	Read	Write
Operation	Balance inquiry / transaction history	Remittance / transfer
Use	Displaying bank balance in the operator app	The foundation of quick deposit
Auth	OAuth 2.0	OAuth + electronic signature

Adopting Method 2 creates room to also provide read APIs, enabling the UX evolution of “integrated display of bank balances inside the operator app.”

Applicable cases

Deposit-flow design for crypto-asset exchange operators — if the current state is Method 1/3 , upgrading to Method 2 is the first UX-improvement candidate
Bank-linkage selection for fintech startups — weighing the EPSP-registration hurdle of Method 2 against the UX improvement
Strategic design of a bank-side BaaS business — for a bank offering Method 2 , the “relationship structure with operators” itself is the differentiator
The current-state analysis section of internal strategy material — a framework for posing the question “which method are we currently operating on”

minna-bank-baas-model — the framework of Minna Bank BaaS’s 2 model (API-provision type × partner-branch type)
japan-financial-regulation — the legal basis for EPSP registration (Payment Services Act / Banking Act)
mercari-bank-license-stack — a concrete example of the license ladder including EPSP

来源: 公開情報整理 (各 BaaS 提供銀行公式サイト・FSA 電代業登録一覧・全国銀行協会発表資料)

Sources

FSA “Points to note when applying for registration as an Electronic Payment Service Provider” (introduction of the registration system through the 2017年 Banking Act amendment; distinction between 第1号 payment instruction / write under Banking Act Article 2 Paragraph 21 and 第2号 account-information retrieval / read) — https://www.fsa.go.jp/common/shinsei/dendai/01.pdf
FSA “Overview of the Electronic Payment Service Provider system” pamphlet (purpose of the system / open innovation) — https://www.fsa.go.jp/common/about/pamphlet/dendaigyo_start.pdf