COCOA - COVID-19 Contact App 4+

Japan MHLW official

Ministry of Health, Labour and Welfare - Japan

    • 1.9 • 97 Ratings
    • Free

iPhone Screenshots


This app is for use in Japan.
Officially provided by the Ministry of Health, Labour and Welfare of Japan (MHLW), this app notifies you of close contact with COVID-19 positive users to help the government and healthcare organizations contain the spread of COVID-19.

■ What you can do
Smartphones with this app will emit radio waves via Bluetooth. When other smartphones with this app receive the radio waves, these will be record in the smartphone.
If you are tested COVID-19 positive and have anonymously registered the positive test result, the app will notify users who were within 1 meter for 15 minutes or more during the period of infectivity.
If it was detected that within the people who came in contact with you there was a positive, you will be notified of the possibility of close contact and guided appropriately.

■ Privacy
No personal information such as your name or phone number is obtained. No geolocation data including GPS data is collected.
All data is saved locally on your smartphone and is automatically deleted after 14 days. Your movements cannot be seen in any way by anyone including government agencies or third parties.
You can stop recording close contacts anytime. Turn off recording the settings in the app or delete the app.

■ Recording close contact
This app records close contact on Android and iOS devices by using Bluetooth and Exposure Notification API provided by Google/Apple.
When you run this app, each smartphone generates a random code. This code changes every 10-20 minutes.
When smartphones with this app are in close contact, they exchange random codes which are stored only on the devices.

■ Close contact notifications
Users tested COVID-19 positive, can choose to share the random codes that their devices have sent out. Each device periodically checks if it has previously encountered any of the shared codes. If the code shared by a COVID-19 positive user matches with a code stored on your device, you will be notified that you have been in close contact with COVID-19 positive user and provide guidance to protect your health.
To receive notifications of close contact , you need to download the app and enable exposure notification function on OS settings. The app only works with others who have the app installed.

■ Support in case of contact with positive registrants
To visualize the close contacts select it from the app or the notifications and you can see the contact period with positive registrants during the last 14 days.
If you are a close contact, please enter information such as physical condition from the app using the symptom input form, and you will be appropriately guided.
For those who are unfamiliar with smartphones, you can be guided via phone call.

■ When you tested positive
When you are tested COVID-19 positive, please register so in the app to notify other users of potential infection. When healthcare organization registers your positive test results to “The Health Center Real-time Information-sharing System on COVID-19” (known as HER-SYS) provided by MHLW,  a processing number is issued to you. Entering this processing number in the app will allow you to register your positive test result.

■ Stop or delete close contact recording
You can stop recording close contacts with other users anytime via app settings. You can delete close contact history (14 days) anytime by deleting the app.

■ Availability
This application will be available until COVID-19 ends.

■ Supported OS versions
iOS 13.5 or higher

■ FAQ & Contact
FAQ (Japanese):

■ Privacy Policy & Terms of Use
Privacy Policy(English):
Terms of Use(English):

What’s New

Version 2.0.1

- Updated part of the tutorial
- Improved the wording and design in the app
- Improved the accessibility
- Fixed a minor bug

Ratings and Reviews

1.9 out of 5
97 Ratings

97 Ratings

I_cycle ,

Network Connection Error

If you want to (or must) use the Exposure Notification system on iOS in Japan, you must use this app. If you attempt to register in the app before you arrive, you will get an unhelpful “Network Connection Error”.

The app will not let you proceed unless you are connected via a Japanese network. Note that international roaming on a foreign cellular network will not work. You must connect via a WiFi network in Japan or via a Japanese cellular network.

yoyookhss ,

Network connection error issue resolved

A lot of people in reviews comments they have network connection error after accepting terms of use. The Japanese Ministry of health website said you cannot use it if you are not in Japan. I assume you will be able to use it once you landed in Japan.
I hope this helps many of you having this issue.

Molanda Zu ,

Needs verification

Thank you for providing the app.

A major limitation is the lack of any feedback that the app is functioning properly and recording close contacts. It is like having a smoke detection without a test button.

I believe showing a count of recent contacts over a period of time does not raise any privacy concerns while at the same time adding a bit of confirmation.

App Privacy

The developer, Ministry of Health, Labour and Welfare - Japan, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy.

Data Not Linked to You

The following data may be collected but it is not linked to your identity:

  • Other Data

Privacy practices may vary, for example, based on the features you use or your age. Learn More

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