---
title: "Sequence Diagram"
site: "Game8 Store – Developer Center"
lang: "en"
category: "Technology & API"
canonical: "https://developers.store.game8.jp/en/sequence/"
---

# Sequence Diagram

📝 This is a reference translation. In case of any discrepancy, the Japanese version prevails.

This page describes the **Out-of-app payment**This page presents the sequence as a diagram.

## In-game item purchase

**Diagram source (mermaid)**

```mermaid
sequenceDiagram
	autonumber
	actor user as User
	participant S8 as Game8 Store
	participant pub as Game (publisherAPI）

	## Select product to purchase

	# Register payment information
	user->>+S8: Send credit card information
	note right of user: Credit card information
	S8->>-user: e-Scott Transaction IDIssue
	note left of S8: Transaction ID

	# Purchase product
	user->>S8: In-game item purchase (sent simultaneously with credit card information)
	note right of user: Transaction ID, In-game user ID, item ID, points to use
	S8->>+pub: In-game item purchase eligibility check (GET /check）
	note right of S8: Transaction ID, In-game user ID, itemID
	pub->>pub: Reserve item
	note right of pub: Transaction ID, In-game user ID, itemID
	pub->>-S8: Return check result
	note left of pub: Purchase eligibility

	opt If a point usage amount is specified
	S8->>S8: Recalculate payment amount
	end
	opt If a balance remains after settlement with points
	S8->>+S8: Execute payment
	note right of S8: Transaction ID, Payment amount, product information
	S8->>-S8: Return payment result
	note left of S8: Transaction ID, Payment status
	end

	# Immediate notification after successful payment
	S8->>+pub: Register in-game item sales record (POST /register）
	note right of S8: Transaction ID, In-game user ID, itemID
	pub->>pub: Grant item
	pub->>-S8: Return item registration result
	note left of pub: Registration result
	S8->>S8: Register purchase result
	note over S8: Transaction ID, User ID, in-game user ID, item ID, payment amount, etc

	# Confirm immediate reflection for the user
	S8->>user: Display purchase completion screen
	note left of S8: Item registration result on the purchase screen
	S8->>user: Send purchase notification email
	note left of S8: Purchase notification email
```