HiJapan Data Breach Exposes 178K Japanese Trade Fair Portal Plaintext Passwords

HEROIC's DarkHive system discovered the HiJapan breach, exposing 177,757 records in August 2025. This Japanese platform suffered a database and combolist compromise that revealed user email addresses and plaintext passwords belonging to Japanese internet users registered on this service.

Why This Is Dangerous

Japanese internet platform breaches exposing plaintext passwords require no cracking and deliver immediately usable credentials for account takeover across Japanese banking, e-commerce, and government service platforms where the same credentials may be active. Japan's high rate of internet service adoption and the prevalence of national platforms like Rakuten, Yahoo Japan, and Japan Post digital services means that credential reuse from Japanese platform breaches creates broad account takeover risk across the Japanese digital economy. Plaintext password exposure from Japanese platforms is actively exploited in automated campaigns targeting Japanese financial services and e-commerce systems.

What Was Exposed

• Email Address
• Plaintext Password

Why This Matters

Japanese internet users whose HiJapan credentials were exposed in plaintext face immediate account takeover risk on Japanese banking, shopping, and government digital platforms where the same login details were reused. Japan's digital payment infrastructure and the high prevalence of connected loyalty and reward programs mean that account compromise can yield direct financial losses through fraudulent purchases and point theft. Anyone who registered on HiJapan must immediately change their password on all Japanese digital platforms where those credentials were used.

How Database and Combolist Breach Works

Japanese internet platforms that store passwords in plaintext create immediately weaponizable credential databases for criminal actors targeting the Japanese digital economy. Attackers exploit web application vulnerabilities to extract these databases, and the plaintext credentials are incorporated into combolists specifically targeting Japanese regional platforms, e-commerce services, and financial applications. These credentials are traded on criminal forums serving threat actors who specialize in targeting Japanese internet users and financial systems.

Check If You Are Affected

HEROIC offers a free identity scanner searching over 400 billion records including data from the HiJapan breach. Visit heroic.com to check if your information was exposed.