Hangul Builder Terms of Use
Established: June 1, 2026 Last updated: October 11, 2026
This is an English translation of the Japanese 「くみたてハングル」アプリ利用規約. It is provided for your convenience. If there is any difference between the two, the Japanese version prevails.
These Terms set out the conditions for using “Hangul Builder” (known in Japan as 「くみたてハングル」; the “App”), a mobile application for learning Hangul provided by AISolve, Inc. (“we,” “us,” or “our”).
These Terms apply as a supplement to our General Terms of Service. If these Terms conflict with the General Terms of Service, these Terms prevail. The General Terms of Service, including governing law (Japanese law) and jurisdiction, are currently available only in Japanese.
Article 1 (About the App)
The App is a mobile application for learning Hangul (the Korean writing system). It provides lessons based on how consonants and vowels are assembled, handwriting practice, reading challenges, vocabulary learning, and other features.
The App is learning material. It does not guarantee any specific learning outcome, such as passing a language proficiency test or acquiring practical Korean conversation skills.
Article 2 (Fees and Paid Plans)
Part of the App is available for free, and part of it is available only after you purchase a paid plan.
2.1 Free content
The learning content for the first two days after you start (Day 1 to Day 2) is available for free.
2.2 Paid plans
To use the learning content from Day 3 onward, you need to purchase one of the following paid plans.
| Plan | Price | Type | Cancellation |
|---|---|---|---|
| Monthly Premium | Price shown in the App Store / Google Play | Auto-renewing monthly subscription | You can stop the next renewal at any time |
| Lifetime Premium | Price shown in the App Store / Google Play | One-time purchase (pay once, use permanently) | — |
| Lifetime Premium (Release Price) | Price shown in the App Store / Google Play | One-time purchase (October 14 to November 30, 2026; Japan only) | — |
Outside Japan, the price is shown in your local currency on the purchase screen of the App and the store where you obtained the App.
2.3 Billing timing and payment
You will be charged the amount shown through the payment method of the platform where you obtained the App (the Apple App Store or the Google Play Store).
Monthly Premium renews automatically for the same period unless you turn off auto-renewal at least 24 hours before the next renewal date. You will be charged within the 24 hours before the renewal date. To turn off auto-renewal, cancel at least 24 hours before the next renewal date in one of the following ways:
- If you purchased through the Apple App Store: on your iPhone, go to Settings > [your name] > Subscriptions
- If you purchased through the Google Play Store: in the Google Play Store app, tap your profile icon > Payments & subscriptions > Subscriptions
Article 3 (Refunds)
Because of the nature of digital content, we do not provide refunds in principle. Refund requests for purchases made through the App Store are handled by Apple under its policies, and refund requests for purchases made through Google Play are handled under Google Play’s policies. For details on refunds, please see our Notation based on the Specified Commercial Transactions Act and the App’s Notation based on the Specified Commercial Transactions Act (both in Japanese).
Article 4 (Learning Data)
- The App stores your learning progress, learning history, badges earned, streak days, and similar data (“Learning Data”) on cloud services we use, such as Firebase.
- Learning Data is stored linked to your account. If you sign in to the same account on multiple devices, your Learning Data is synced.
- You can download your own Learning Data in JSON format from the account settings screen of the App. The download URL expires 24 hours after it is issued.
- If your network connection is unstable, syncing of Learning Data may be delayed. We are not responsible for any damage caused by delayed or failed syncing.
Article 5 (Account Deletion)
5.1 How to delete your account
You can request deletion of your account at any time from the account settings screen of the App. The deletion request goes through the following two confirmation steps:
- Reviewing the warnings about deletion, and an optional data export
- Confirming by typing the word shown for deletion, and signing in again
If it is difficult to complete the procedure in the App, for example because you have already uninstalled it, you can also request account deletion by email ([email protected]). To prevent impersonation, we will verify your identity, for example by asking you to send the request from your registered email address. After verification is complete, we will completely delete your data after the 30-day grace period in Article 5.2.
5.2 When deletion happens
We completely delete your data after a 30-day grace period from when we receive your account deletion request. You can cancel the deletion by signing in again during the grace period.
Separately, an anonymous account (if you use the App without registering an email address or similar) is deleted automatically by us if it is not used for 180 days after the last sign-in, whether or not a deletion request has been made. However, anonymous accounts with a purchase history for a paid plan are excluded from this automatic deletion. For details, please see Article 7 of our Privacy Policy.
5.3 Data that is deleted
The following data is deleted:
- Firebase authentication information (email address, sign-in provider information)
- Profile information
- Learning progress data (consonants, vowels, tense consonants, complex vowels, syllables, handwriting, reading, vocabulary)
- Vocabulary quiz results
- SRS (spaced repetition) cards, study session records, and the weak-point cache
- Gamification information (experience points, streak days, badges)
- Learning statistics, roadmap progress, learning cycle progress (how many days you have completed), and module completion flags
- Subscription information (on the App side)
- Device information and push notification tokens
- Notification delivery logs
- Your files on Firebase Storage (such as the JSON file for data export)
5.4 Data that is not deleted
The following data is not deleted:
| Data | Handling |
|---|---|
| Deletion audit logs (a one-way hash of the UID and a breakdown of what was deleted) | Kept permanently in a form that cannot identify you (to respond to fraud and legal disputes) |
| Payment history held by payment providers (Apple, Google, RevenueCat) | Follows each provider’s policy |
| Storage on your device (learning settings, cache, etc.) | Deleted when you uninstall the App |
| Usage logs in Firebase Analytics and Crashlytics | Follow Google’s policies for each service |
5.5 Important
Data cannot be recovered after deletion is complete.
Deleting your account does not automatically cancel a paid subscription.
If you do not want to continue your subscription, cancel it separately from the subscription management screen of the platform where you purchased it (the Apple App Store or the Google Play Store). See Article 2.3 for the steps. After your account is deleted, you will continue to be charged unless you cancel on that platform.
Article 6 (Age Requirement)
The App is intended for people aged 13 and older. If you are under 13, please do not use the App. If you are 13 or older but under 18, please use the App with the consent of a parent or guardian.
Article 7 (Disclaimer Regarding Content)
- The learning content provided in the App is material edited independently by us. We take reasonable care regarding its accuracy, but we make no warranty as to its completeness, accuracy, usefulness, or fitness for a particular purpose.
- We make no guarantee regarding learning outcomes from the App (such as improved language ability, passing or failing a proficiency test, or proficiency in Hangul).
Article 8 (Privacy)
Personal information in the App is handled in accordance with our Privacy Policy.
Article 9 (Changes)
These Terms are changed through the same procedure as our General Terms of Service. For important changes, we will notify you in advance of the changes and their effective date through a notice in the App or by email to your registered email address.
Established: June 1, 2026 Last updated: October 11, 2026
AISolve, Inc.