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Privacy Policy

Last updated: April 15, 2026

TKwriteworks Co., Ltd. ("we," "us," or "our") operates Yohaku (accessible at https://yohaku-seo.com), an AI-powered Japanese SEO article generation service. This Privacy Policy explains how we collect, use, disclose, and safeguard your information when you use our service.

1. Information We Collect

Account Information

When you create an account, we collect your name, email address, and password. If you sign up via a third-party provider (such as Google), we receive your name and email from that provider.

Usage Data

We automatically collect information about how you interact with our service, including pages visited, features used, article generation history, and timestamps of activity.

Payment Information

Payment processing is handled by Stripe. We do not store your credit card number or full payment details on our servers. Stripe may collect and store your payment information in accordance with their privacy policy.

Cookies and Tracking

We use cookies and similar technologies to maintain your session, remember your preferences, and analyze usage patterns. You can control cookies through your browser settings.

2. How We Use Your Information

  • To provide, operate, and maintain the Yohaku service
  • To process your subscription and manage billing
  • To generate AI-powered Japanese SEO articles based on your inputs
  • To improve our service, including AI model outputs and user experience
  • To communicate with you about your account, updates, and support requests
  • To detect and prevent fraud, abuse, or security incidents
  • To comply with legal obligations

3. Data Sharing

We do not sell your personal information. We share data with the following third-party service providers solely to operate our service:

  • Stripe — Payment processing and subscription management
  • Google APIs — Google Search Console and Google Analytics integration for SEO analytics features
  • Supabase — Database hosting, authentication, and data storage
  • AI Providers (Google Gemini) — Article generation processing. Your input prompts and brand information are sent to AI providers to generate content.
  • Vercel — Application hosting and delivery

4. Data Security

We implement industry-standard security measures to protect your information, including encryption in transit (TLS), encrypted storage, row-level security policies on our database, and secure API key management. However, no method of electronic transmission or storage is 100% secure, and we cannot guarantee absolute security.

5. Data Retention

We retain your account data and generated articles for as long as your account is active. If you delete your account, we will delete your personal data within 30 days, except where retention is required by law or for legitimate business purposes (such as fraud prevention or financial record-keeping).

6. Your Rights

You have the right to:

  • Access your personal data that we hold
  • Correct inaccurate or incomplete data
  • Delete your account and associated data
  • Export your generated articles and account data
  • Withdraw consent for optional data processing

To exercise any of these rights, please contact us at support@yohaku-seo.com.

7. Cookies

We use the following types of cookies:

  • Essential cookies — Required for authentication and core functionality
  • Analytics cookies — Help us understand how you use the service to improve it
  • Preference cookies — Remember your settings and preferences

You can disable non-essential cookies through your browser settings. Disabling essential cookies may prevent you from using certain features of the service.

8. Third-Party Services

Our service integrates with third-party services, each governed by their own privacy policies:

9. Changes to This Policy

We may update this Privacy Policy from time to time. We will notify you of any material changes by posting the updated policy on this page and updating the "Last updated" date. Your continued use of the service after such changes constitutes acceptance of the updated policy.

10. Contact Information

If you have any questions about this Privacy Policy, please contact us at: