By Sagar V. Mankar 
An attorney for Nintendo has recently shared the company’s position on emulation and what constitutes illegal activity under Japanese law.
Koji Nishiura, a patent attorney and deputy general manager of Nintendo’s intellectual property department, spoke on this topic during a lecture titled “The Importance of Intellectual Property Rights in the Game Industry” at the Tokyo eSports Festa 2025 (Denfaminicogamer, via Automaton).
Nishiura addressed the question, “Are emulators illegal or not?” While he noted that emulators are “not inherently illegal“, their legality depends on “how they are used.” For example, if an emulator copies a program from the game device it mimics, it would violate copyright laws. Additionally, if an emulator disables security mechanisms like encryption—referred to as “technical protection measures“—it would breach Japan’s Unfair Competition Prevention Act. Similar regulations exist in copyright laws outside Japan.
This legal distinction is why Nintendo has actively pursued lawsuits and issued warnings against certain Switch emulators. Nishiura highlighted that these emulators often disable Nintendo’s security protections, which the company considers a significant violation. Furthermore, he mentioned that emulators containing links to pirated games, described as “reach apps” under Japanese law, also constitute copyright infringement.
Recent Actions Against Emulators
Nintendo’s stance isn’t just talk – the company has taken action to protect its games. A notable example occurred last year when Nintendo sued Yuzu, a popular Switch emulator. The lawsuit ended with Yuzu’s developers, Tropical Haze, agreeing to shut down the emulator and pay Nintendo $2.4 million in damages. The company claimed that over a million copies of The Legend of Zelda: Tears of the Kingdom were pirated before its official release using this emulator.
In October 2024, they contacted the Switch emulator Ryujinx to cease operations. A month later, they even claimed ownership of the Ryujinx domain.
Also last year, the Game Boy emulator Pizza Emulators was pulled from the Google Play store following a lawsuit settlement with Nintendo.
Nintendo has recently expanded its focus to include unauthorized online services. The company warned players about security risks from services that try to replace official online features for the Wii U, which stopped operating in April 2024. This warning came after fan groups like Pretendo managed to restore online functionality to Wii U games just one day after Nintendo’s official servers shut down.