Three Japanese credit card companies are investigating why processing of payments came to a standstill for several hours on Saturday.
Major credit card company JCB says some of its member stores started having problems after 11 AM.
The company says some kind of failure occurred on Japan Card Network's credit card settlement system.
Some people who tried to use credit cards issued by Mitsubishi UFJ Nicos and Jaccs that use the same system were also unable to settle their payments.
The system was restored by around 5:20 PM.
East Japan Railway Company's online reservation system, known as "Eki Net", also experienced disruptions from around 11 AM on Saturday.
Users were unable to use some of the services, including making changes to reservations or ordering new tickets, until the system was restored at around 6:30 PM.
The railway company is investigating the cause of the failure.