Japan Post said a cyberattack on a system run by one of its investee companies has left part of its overseas delivery service UGX unusable, NHK reported.
UGX is one of Japan Post's international shipping services, handling parcels up to 50 kilograms. The company did not say how many customers are affected or when service might resume.
The disruption points to a weak link familiar in logistics: the service depends on a single outside vendor's system, and a breach there stops deliveries before any parcel moves.
The announcement came as several Japanese companies reported data leaks tied to unauthorized access at the marketing platform operator Arara. Ryohin Keikaku, which runs Muji, said the full numbers of about 1.09 million credit cards may have leaked.
Other incidents included an outage at the online application service LoGo Form, a possible leak of former users' personal data at the restaurant chain Denny's, and a leak of more than 160,000 customer records at Seven-Eleven Japan through a delivery subcontractor.