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ネット安全2026/06/30

[Warning] Could Your Information Be Leaking? Checking for Personal Data Breaches and Countermeasures!

Summary (addressed to family): Your important personal information might have leaked online without you knowing. Let's learn together how to check and how to protect it!

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Hello! I'm Shemihaza, the Guardian (Sentinel). Today, let's start with a somewhat scary topic. Did you know that your valuable email addresses, passwords, names, and addresses might have leaked somewhere on the internet? You might think, 'Not me!', but many people are actually falling victim without realizing it. This time, let's look together at how to check if your information has leaked and what to do if it has.

How do personal data breaches happen?

  • ① Information leaks from stores or services you use: You sometimes hear news like, 'Customer information leaked from Company XX,' right? Services you've registered for can be hit by cyberattacks, and the personal information stored there can be stolen.
  • ② Being tricked by dangerous websites or emails: There are cases where you're led to fake websites and enter your passwords or other information, or you open an email with a virus, and your computer or smartphone gets hijacked, leading to information theft.
  • ③ Stolen information being sold on the 'dark web': Once information leaks, it can be bought and sold among malicious individuals on the internet's black market, known as the 'dark web'. Based on this, there's a risk it could be used for even worse purposes.

How to check if your money or information has leaked

There's a free service where you can check if your information has leaked. On a site called 'Have I Been Pwned?', you can simply enter your email address to find out if there have been any past data breaches involving it.

  • Check if you've searched for your email address on 'Have I Been Pwned?'
  • If 'Oh no — pwned!' is displayed, check which service leaked your information.
  • Check if you've immediately changed the password for the service where a leak was found.
  • Check if you've reused the same password on other sites, and if you've changed all of them to different passwords.
  • If possible, check if you've set up two-factor authentication (a system for identity verification using a method other than just a password).
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Where to seek help when in trouble

If your personal information has leaked and you feel anxious or have actually fallen victim, please don't hesitate to seek help immediately instead of worrying alone. The Consumer Hotline (188) and the Police Consultation Dial (#9110) are there to help you. If unauthorized credit card use is confirmed, call your card company immediately to process a suspension. Prompt action is key to minimizing damage. Let's work together to create a safe and secure online environment!

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