Established: October 22, 2026
This is an English translation of the Japanese Privacy Policy (プライバシーポリシー) at https://physdraft.com/privacy. If the Japanese version and this English version differ in any way, the Japanese version prevails.
PhysDraft (the "Operator") handles the personal information that it deals with in the learning service "PhysDraft" (the app: https://open.physdraft.com/; the "Service") and on the introductory homepage (https://physdraft.com/) in accordance with this Policy, complying with laws and regulations such as the Act on the Protection of Personal Information (the "APPI").
1. The Operator (Personal Information Handling Business Operator)
| Item | Content |
|---|---|
| Name | PhysDraft |
| Address | Japan (primary base) and the United States. The full address will be provided without delay upon request |
| Representative | 芦澤 知樹 |
| Contact | physdraft@gmail.com |
2. Information We Collect
2-1. Information that Users enter or send
| Information | When it is collected | Notes |
|---|---|---|
| Display name (1 to 40 characters) | When registering an account, when changing it in settings | It does not have to be your real name. It is not visible to other Users (it appears in the Operator's admin screen) |
| Icon image (optional) | When you upload an image in settings | Only a JPEG that the browser has cropped to a 256-pixel square is sent |
| Images of problems | When you send a problem | PNG, JPEG and WebP; up to 8 images at a time, up to 10 MB each. The original is stored as it is (location information in photos (Exif) is not removed either). A small picture (JPEG) shown on the card is also created in the browser and sent together |
| Passkey information | When registering an account, when adding a passkey | Public key, passkey ID, a usage counter, the connection method and type of the device, whether it is synchronized, the date and time of creation, and the date and time of last use. We do not receive the private key or fingerprint or face information (they stay on the device) |
| Contents of inquiries | When you inquire by e-mail | E-mail address and message body. Received at physdraft@gmail.com (Google's Gmail) |
2-2. Information that the Service records
| Information | Content |
|---|---|
| Record of problems sent | Date and time sent, status (waiting, being solved, finished, error), the AI model used and its version, number of round trips, cost, amount used (number of tokens), the name of the provider that returned the response, content of errors, date and time of deletion |
| Results of the AI | The answer, the explanation, the scene the AI built, the whole exchange with the AI (images of problems are recorded by name only), images of scenes the AI drew for checking, and the parts the engine could not build |
| Status of use | Date and time of registration, whether approved and the operator's mark, "days of visit" (one row per User per day), the number of times sent this week |
| Record of invitations | For invitation links the Operator created: expiry date, who used it, date and time of cancellation, and a memo about the addressee (free text the Operator writes, such as a name or nickname) |
| Evaluations | A 3-level evaluation and a free-text memo that the Operator attaches to the results of problems sent |
| Login mark | A cookie (7 below) |
2-3. Information we do not collect
We do not collect e-mail addresses (except for inquiries), phone numbers, addresses, dates of birth, passwords, school names, payment information, device location information, or advertising identifiers. The Service has no code that stores a User's IP address or browser type (however, Cloudflare, which relays communications, processes them; see 5 below).
2-4. The homepage
The homepage (https://physdraft.com/) does not use cookies, localStorage, access analytics or advertising. Fonts and videos are also served from our own server. Links to external sites placed on the page (such as X) take you to that site only when you click them.
3. Purposes of Use
The Operator uses personal information for the following purposes.
- To provide the Service (authenticating accounts, reading images of problems and creating simulations, displaying results, and the settings functions)
- To manage the number of uses, to prevent improper use (such as avoiding the usage limit with multiple accounts), and to manage costs
- To improve the quality of the Service. Persons designated by the Operator as administrators look at the problems and results sent, and use them to improve the engine and the AI (the instructions and the mechanism) and to check the accuracy of results
- To reply to inquiries and to contact Users
- To investigate failures, to ensure security, and to respond to acts that violate the Terms
- To create statistics in a form that cannot identify individuals (number of Users, number of problems sent, costs, etc.) and use them for the Operator's decisions and for introducing the Service
- When paid plans start, to bill fees and confirm payments (the information collected and the recipients will be added to this Policy and announced when paid plans start)
The purposes of use may be changed within a range that is reasonably recognized as related to the purposes before the change. When we change them, we will announce it by posting it in this Policy.
4. Information Sent to the AI
- When you send a problem, the Operator's server (a virtual machine of Microsoft Azure in Japan) sends the image of the problem and the instructions to OpenRouter, the AI gateway. OpenRouter passes the request on to the business that runs the AI model.
- What is sent: the image of the problem (the original), the instructions and the engine source code written by the Operator, images of scenes for checking the scene the AI built, and the exchange itself. Display names and User IDs are not sent to the AI.
- The default model of the Service is
openai/gpt-6-luna(an OpenAI model, via OpenRouter). The model and the business that returns the response may change. The name of the business that returned the response is recorded for each problem sent. - The OpenRouter account is set not to use providers that use paid usage content to train models.
- The Operator does not currently use the problems sent to train AI models themselves (for example, fine-tuning).
- Whether OpenRouter and the businesses that run the models store the inputs, and for how long, depends on each business's own rules. The Operator cannot control this itself.
- Request: Please make sure that no personal information of yourself or others (such as names, face photos, addresses, answer sheets or name lists showing a school name) appears in the images of problems. Photograph only the part of the problem, and turn off location information (Exif).
5. Provision to Third Parties and External Services
- The Operator does not provide personal data to third parties except in the following cases.
- When the User has given consent
- When required by laws and regulations
- When necessary to protect a person's life, body or property and it is difficult to obtain the person's consent
- When especially necessary for improving public health or promoting the sound growth of children and it is difficult to obtain the person's consent
- When it is necessary to cooperate with a national agency or the like in performing duties prescribed by laws and regulations
- To run the Service, the Operator uses the following external services. The Operator may entrust the handling of personal data to these businesses. When it does, it checks, to the necessary extent, that the business handles the personal data safely.
| Business | How it is used | Information handled | Location |
|---|---|---|---|
| Cloudflare, Inc. (Workers, D1, R2) | Providing the screens and the API, storing the database and files, relaying communications (the same applies to the homepage) | All the information in 2 | The database and files are set to be placed in the Asia-Pacific (APAC) region (no specific country is specified) |
| Microsoft (Azure virtual machine) | Processing that calls the AI (sends images of problems to OpenRouter and returns results to Cloudflare) | Images of problems, results of the AI (only while being solved; deleted when finished) | Japan (East Japan) |
| OpenRouter | Passing requests on to AI models | Images of problems, instructions, exchange with the AI | The United States (as far as the Operator understands) |
| Businesses that run AI models (currently OpenAI has been confirmed; OpenRouter chooses) | Reading images of problems and building simulations | Images of problems, exchange with the AI | Depends on the business (OpenAI, currently confirmed, is in the United States) |
| Google (Gmail) | Receiving e-mails of inquiries | E-mail address, message body | Decided by Google (the company is in the United States) |
- The Operator does not currently use external logging or analytics services such as LangSmith, Sentry or Datadog, or e-mail sending, payment or advertising services. If we start using them, we will add them to this Policy.
- If the Operator's business is taken over (including when the Operator is incorporated), personal information may be handed to the successor. It will still be handled within the scope of this Policy.
6. Provision to Third Parties in Foreign Countries
- As the table above shows, images of problems and the like are sent to, or handled by, businesses in foreign countries (OpenRouter and the businesses that run the models, Cloudflare, etc.). By registering an account and using the Service, the User is treated as having consented to this. If you do not consent, please do not use the Service.
- Regarding provision to third parties in foreign countries, we provide the following information under Article 28 of the APPI.
| Recipient | Country of location | The country's system for protecting personal information | Measures taken by the recipient |
|---|---|---|---|
| OpenRouter | The United States (as far as the Operator understands) | The United States has no single comprehensive law on the protection of personal information; it is covered by sector-specific federal laws and by state laws (as far as the Operator understands). For details, see the "Survey on systems for the protection of personal information in foreign countries" published by the Personal Information Protection Commission | Handled in accordance with the terms of use, privacy policy and data-processing terms that OpenRouter publishes. The Operator uses a setting that does not use providers that train on the data |
| Businesses that run the models (OpenAI, etc.) | Depends on the business (OpenAI, currently confirmed, is in the United States) | Same as above (if a business outside the United States is used, that country's system applies) | Handled in accordance with the terms that each business publishes |
| Cloudflare, Inc. | The company is in the United States. The data is placed in the APAC region | Same as above | Handled in accordance with the terms that Cloudflare publishes |
| Microsoft | The company is in the United States. The data is placed in a region in Japan and handled only while being solved | Same as above | Handled in accordance with the terms that Microsoft publishes |
- The Operator checks, to the necessary extent, that these businesses handle personal data appropriately, and reviews the handling if there is a problem.
7. Cookies and the Like
| Name | Purpose | Duration and nature |
|---|---|---|
Cookie pd_session |
A login mark. It contains the User's ID, the expiry date and a signature | 30 days. Set so that it cannot be read by the page's scripts (HttpOnly). Set not to be attached to requests sent from other sites (SameSite=Lax). Secure on https |
localStorage physdraft.notifyDone |
A mark that you turned on "notify me when solving is finished" | Remains on the device. Removed when you turn it off in settings |
- The Operator's admin screen (not visible to Users) uses separate cookies and localStorage for its display settings.
- The notification that solving has finished is shown only inside your device, by a browser function. No external server for notifications and no e-mail is used.
- The Service's screens do not send Users' information to third-party servers other than the Service. We do not use cookies for advertising or access analytics. We do not provide cookies or other identifiers to third parties.
- Because nothing is recorded on the server side when you log out, that cookie can still be used to log in until its expiry (30 days). On a shared device, please delete the browser's cookies when you have finished.
8. Where, How Long and How We Store and Delete
| Information | Where stored | Period and deletion |
|---|---|---|
| Account information (display name, passkeys, days of visit, etc.) | Cloudflare D1 (APAC) | No automatic deletion period is set. Deleted on a withdrawal request. Passkeys can be deleted at any time in settings (except the last one) |
| Icon image | Cloudflare R2 (APAC) | Can be removed at any time in settings |
| Images of problems, results, exchange with the AI | Cloudflare R2 (APAC) | No automatic deletion period is set. Can be deleted at any time with "Delete this problem" on the screen (cannot be restored) |
| Record of problems sent (date and time, model, cost, status, etc.) | Cloudflare D1 (APAC) | Even after "Delete this problem", it remains to count the number of times, costs and evaluations (the images and results are deleted) |
| Files while being solved | Azure virtual machine (Japan) | Deleted when the results have been sent to Cloudflare. Results not yet sent remain until they arrive |
| History for restoring the database | Cloudflare D1 | Up to 7 days. No other backup is taken |
| E-mails of inquiries | Gmail | Stored to respond to inquiries; deleted when deletion is requested or when the Service ends |
- The Operator has not set a retention period. Personal data is kept until the User deletes it, withdraws, or asks for its deletion, and is deleted when the Service ends. When it becomes clear that the data is no longer needed, the Operator endeavors to delete it without delay.
- On withdrawal, the Operator deletes the account information. Because the app currently has no function for withdrawing from the screen, please contact us (Terms of Service, Article 9). Before withdrawing, please delete the problems you sent with "Delete this problem" on the screen. If the images and results of the problems sent remain without having been deleted, the Operator will delete them when you ask (this requires work by the Operator and may take time).
9. Security Control Measures
To prevent leakage, loss and damage of personal data, the Operator takes the following measures.
- Organizational: The Operator's persons who can see personal data are limited to those designated as administrators. The admin screen runs as a separate app from the Users' screens (a separate domain and a separate signing key).
- Human: The Operator informs the members who handle personal data of the contents of this Policy.
- Physical: Personal data is stored in the data centers of cloud providers (Cloudflare, Microsoft). Entry and exit control of the data centers is carried out by these providers. The Operator may display or take out data on the Operator's devices for checking and improvement work. The Operator endeavors to delete the data taken out once it is no longer needed.
- Technical:
- We hold no passwords (passkeys only). Because the server holds only public keys, a leak of the data would not by itself allow anyone to log in.
- Communications are encrypted with https. Communications between the Operator's servers (Cloudflare and Azure) are protected by signatures (HMAC-SHA256). The Azure virtual machine does not hold the keys to the database or file storage.
- The file storage is not public; files are served to Users' screens in a way that only the logged-in owner can see them. Other people's problems cannot be seen.
- Cookies are signed, and we check requests to prevent sending from other sites.
- Uploaded images are checked for type and size.
- Login to the virtual machine is by key only.
- Understanding the external environment: We are aware that personal data is handled on servers and services of the foreign businesses in the table above, and take the necessary measures.
10. Requests for Disclosure, Correction, Cessation of Use, etc. of Retained Personal Data
- Regarding the information that the Operator holds that can identify a User (retained personal data), the User can make the following requests.
- Notification of the purposes of use, and disclosure (including disclosure by electronic means)
- Correction, addition or deletion of content
- Cessation of use or deletion, and cessation of provision to third parties (where allowed by law)
- Disclosure of records of provision to third parties
- Users themselves can, from the settings screen, change the display name and icon and add or delete passkeys, and can delete the images and results of the problems they sent with "Delete this problem".
- Please send requests by e-mail to physdraft@gmail.com.
- Identity verification: Because the Service does not register e-mail addresses, we confirm that you are the person concerned using information the Operator has recorded, such as the display name, the date of registration, and the date and time of problems sent.
- Fee: None (free of charge).
- Reply: We will reply without delay.
- Depending on the content of the request, we may be unable to comply, as provided by law. In that case, we will tell you the reason.
11. Minors
People under 18 must obtain the consent of a person with parental authority (a guardian) before using the Service. Regarding the handling of the personal information of people under 18, if a person with parental authority asks, the Operator will respond in accordance with the requests in Section 10.
12. When a Leak or the Like Occurs
If a leak or the like of personal data occurs and there is a high risk of harming individuals' rights and interests, we will report it to the Personal Information Protection Commission and notify the persons concerned, in accordance with laws and regulations.
13. Links to External Sites
The homepage and the Service contain links to external sites. This Policy does not extend to the handling of personal information on the linked sites.
14. Changes to This Policy
The Operator may change this Policy in line with changes in laws and regulations or in the Service. When it does, it will announce it on the Service's screen or the homepage. For important changes, such as changes in the purposes of use or changes in provision to businesses in foreign countries, we will announce them a reasonable period before the effective date.
15. Contact for Inquiries
This is the contact for inquiries, complaints and requests about this Policy and the handling of personal information.
- E-mail: physdraft@gmail.com (the Operator is as stated in Section 1 above)