OtoOi Privacy Policy

Last updated: October 25, 2026 Established: June 2, 2026

Yutaka Imai (trade name: OtoOi; "we" or "us") sets out this Privacy Policy (the "Policy") on how we handle users' information in "OtoOi" (the "Service"), a language learning service.

This is an English translation of the Japanese Privacy Policy. The Japanese version is the official text (Section 16).

1. Who we are

• Service: OtoOi, including the Korean reading app "OtoOi Reader" (app version and web version at app.otooi.com) and the website otooi.com
• Operator: Yutaka Imai (sole proprietor; trade name: OtoOi)
• Address: Plus One 402, 3-14-34 Kamiosaki, Shinagawa-ku, Tokyo 141-0021, Japan
• Contact: privacy@otooi.com
• Information on paid services: Legal notice under the Act on Specified Commercial Transactions (in Japanese)

2. Information we collect

We collect the following information to provide the Service. This section lists both the information we actually collect now and information we may collect in the future.

2.1 User identifier (current)

The Service does not require account registration with your name or email address.

The app version of the Service (iOS and Android) assigns a user identifier (user ID) to each device at startup, through anonymous authentication on an authentication platform (Firebase Authentication). We do not collect your name, email address or similar. We use this user identifier to check whether you have a subscription and provide subscriber content (explanations and notes for pieces, etc.), to manage subscriptions (Section 2.6), and to analyze how the Service is used (Section 2.4). If you delete and reinstall the app or change devices, a new user identifier is assigned (you can carry over your subscription with "Restore Purchases").

The web version (app.otooi.com) does not use authentication.

2.2 Learning records (current)

The Service stores your learning records (pieces you have read, marks such as "Read" and "Known", display settings, etc.) only on your device (in the app's storage, your browser's local storage, etc.) and does not send them to our servers. They are lost if you erase the data through your device or browser settings or delete the app (see also Section 7 and the Terms of Use).

2.3 Information collected automatically when you access the Service (current)

When the Service is delivered (hosting and CDN), technical information such as your IP address, browser type and version, date and time of access and referrer may be recorded in the logs of our service providers (Section 5).

2.4 Information collected through cookies and analytics tools (may be used)

To understand and improve how the Service is used, we may use cookies, similar technologies and analytics tools (including Google Analytics / GA4). Through these, we may collect information about your browsing and actions (including identifiers such as cookies). We do not use cookies for advertising (such as targeted advertising).

The app version of the Service uses Google Analytics for Firebase for the same purposes. Instead of cookies, the app version uses an identifier that Google Analytics assigns to each app installation (app instance ID). We do not collect advertising identifiers (such as the IDFA) or the iOS identifier for vendors (IDFV). To analyze usage together with subscription status, we send the user identifier (Section 2.1) to Google Analytics (it does not include your name, email address or similar).

The Service is provided to users in countries and regions including Japan (it is not offered to residents of the European Economic Area (EEA), the United Kingdom or Switzerland; Section 10). We use the analytics cookies, etc. described above for these users. The recipients, the information sent, the purposes, and how to stop analytics are described in Section 14 (Disclosure of external transmission).

If we start offering the Service to residents of the EEA, the United Kingdom or Switzerland, we will separately take the steps required by the laws of those regions (such as the GDPR), including obtaining prior consent for the use of analytics cookies, etc. (the Service is designed so that prior consent can be required or not depending on the jurisdiction).

Cookies and local storage that are necessary to provide the Service, such as for keeping you authenticated, are used whether or not analytics is stopped.

2.5 Information used to prevent misuse (current)

To prevent misuse of the Service, we may check information about your device, app and browser through security services provided by external providers.

2.6 Subscription information (current)

Payments for subscriptions (paid plans) in the app version are processed by the operator of the app store (Apple, for the App Store). We do not obtain payment information such as credit card numbers. To check whether you have a subscription and when it expires, and to manage subscriptions, we use the services of RevenueCat, Inc. and obtain your purchase history (products purchased, dates and times of purchases, renewals and cancellations, subscription status, etc.) linked to your user identifier (Section 2.1).

2.7 Information we may collect in the future

As we add features to the Service, we may collect:

• Information you provide when you contact us or receive support

3. Purposes of use

We use the information we collect for the following purposes:

1. To provide, maintain and protect the Service
2. To assign user identifiers and check whether you have a subscription
3. To provide learning features and to measure and visualize learning progress
4. To analyze how the Service is used, improve its quality and develop new features
5. To prevent misuse and ensure security
6. To respond to inquiries and support requests
7. To provide and manage subscriptions (paid plans) (payments are processed by the operator of the app store)
8. To notify you about the Service, changes to its terms, etc. (by posting in the Service, etc.)
9. To comply with laws and regulations and respond to them

4. Provision to third parties

We do not provide the information we collect to third parties except in the following cases:

1. With your consent
2. As required by law
3. When it is necessary to protect a person's life, body or property and it is difficult to obtain your consent
4. In connection with a business succession (such as a merger or transfer of business)

Having our service providers handle information under Section 5 does not constitute provision to third parties (see Section 5).

5. Service providers and external services

We may entrust the handling of information to the following service providers to the extent necessary to provide the Service. Provision of information to these service providers does not constitute provision to third parties under the Act on the Protection of Personal Information of Japan. We supervise our service providers appropriately.

Each provider's handling of information is also subject to its own privacy policy.

6. Provision to third parties in foreign countries (international transfers)

The service providers in Section 5 include companies that store and process information outside Japan, specifically Google, Cloudflare, Apple, RevenueCat and others (in the United States and elsewhere). User identifiers, purchase history, etc. are also stored and processed on the servers of these providers (including servers outside Japan). When we provide information to these third parties in foreign countries, we take the necessary measures in accordance with applicable laws.

7. Retention period

• We keep user identifiers and purchase history while you use the Service. If you ask us to delete them, or if a reason that we separately define (such as inactivity) arises, we will erase them appropriately, except for information we are required by law to keep.
• Learning records on your device are kept on your device until you delete them.
• Logs of our service providers, etc. are kept for the periods set by each provider.

8. Security measures

We take necessary and appropriate measures to prevent the leakage, loss or damage of the information we collect and otherwise to manage it securely.

9. Your rights (requests for disclosure, correction, deletion, etc.)

You may request disclosure, correction, addition, deletion, suspension of use, etc. of your information that we hold (including your user identifier and purchase history). Please contact us at the address in Section 1. After verifying your identity, we will respond without delay in accordance with the law.

You can delete the learning records stored on your device at any time yourself, by deleting the app or through your browser settings.

10. Scope of this Policy

The Service is provided to users in countries and regions including Japan (the app version is offered in the app stores of the countries and regions where it is distributed). We do not currently offer the Service to residents of the European Economic Area (EEA), the United Kingdom or Switzerland. If we start offering the Service to residents of these regions, we will set out handling that complies with their laws (such as the GDPR) and revise this Policy.

We handle the information of users outside Japan in accordance with this Policy as well. As described in Section 6, information is stored and processed on the servers of our service providers, including outside Japan (in the United States and elsewhere). If the laws of the country or region where you live give you rights in addition to those set out in this Policy, we will respond in accordance with those laws.

11. Use by minors

The Service is intended mainly for adult learners. Minors who use the Service must do so with the consent of a parent or guardian.

12. Changes to this Policy

We may change this Policy in response to changes in laws or in the Service. If we make important changes, we will announce them by posting in the Service or by other means.

13. Contact

For inquiries about this Policy, please contact:

• privacy@otooi.com

14. Disclosure of external transmission

The Service uses mechanisms (such as tags) that cause your device to send information to companies other than us (external companies). As required by the Telecommunications Business Act of Japan, we disclose the details of this external transmission as follows.

How to stop analytics

You can stop the sending of information for analytics described above as follows:

• Website and web version: delete or disable cookies in your browser settings, or use the "Google Analytics Opt-out Browser Add-on" provided by Google (https://tools.google.com/dlpage/gaoptout)
• App version: delete the app

Google's handling of information is also subject to Google's Privacy Policy (https://policies.google.com/privacy).

For how consent will be handled if we start offering the Service to residents of the EEA, the United Kingdom or Switzerland, see Section 2.4.

15. Use of YouTube API Services

The Service (including otooi.com and related tools we operate) uses YouTube API Services to publish and manage the videos we post on YouTube.

1. Our website introduces and links to videos published on our YouTube channel (and may embed them in the future).
2. The only information we obtain and store through YouTube API Services is information about our own channel (identifiers of videos and playlists, privacy settings, statistics, etc.). We do not obtain users' YouTube account information or viewing history. If we change the scope of the information we obtain in the future, we will revise this Policy and announce it in the Service (Section 12).
3. Use of YouTube API Services is subject to the YouTube Terms of Service and Google's Privacy Policy.
   • YouTube Terms of Service: https://www.youtube.com/t/terms
   • Google Privacy Policy: https://policies.google.com/privacy
4. If you have granted the Service or our tools access through your Google account, you can revoke that access at any time on Google's security settings page (https://myaccount.google.com/connections).
5. For requests to delete information we hold, etc., see Section 7 (Retention period) and Section 9 (Your rights).

16. Language

The Japanese text of this Policy is the official version. If there is any discrepancy between a translation of this Policy (including this English version) and the Japanese version, the Japanese version prevails.