Nintendo, maker of the Wii game console, has admitted a data breach but says no personal or company information was exposed.
The Japanese company revealed Sunday that the server of an affiliate of its U.S. unit was accessed illegally a few weeks ago.
"There were no third-party victims," said company spokesman Ken Toyoda, calling it a "possible hacking attack."
The incident recalls Sony Corp's recent serious data breach.
In April, the Sony said the personal information of more than 100 million users, including email addresses, names and birth dates, is suspected of having been stolen after security was compromised in April for its network service for the PlayStation 3 game.
Both Sony and Nintendo are based in Kyoto.
Sony had to shut down its PlayStation and online entertainment networks, re-starting it at the beginning of June. It has contacted the FBI and other authorities for an investigation into the cyber attacks.
Though Sony officials claim they had shored up their online security, a group of hackers, who call themselves Lulz Security — a reference to the internetspeak for "laugh out loud" — proved Sony wrong.
The group says it broke into the Sony Pictures website and compromised the information of 1 million users. The hackers post the data, including passwords, online.