Nintendo's aggressive stance against emulation is well-documented. Recent examples include the $2.4 million settlement with Yuzu developers in March 2024, the October 2024 cessation of Ryujinx development following Nintendo's intervention, and the legal advice preventing a full Steam release of the Gamecube/Wii emulator Dolphin in 2023 due to Nintendo's legal pressure on Valve. The 2023 case against Gary Bowser, who sold devices circumventing Nintendo Switch anti-piracy measures, resulted in a $14.5 million judgment.

A Nintendo patent attorney, Koji Nishiura, recently shed light on the company's strategy at Tokyo eSports Festa 2025. While acknowledging that emulators aren't inherently illegal, Nishiura emphasized that their use can become illegal under certain circumstances. Specifically, emulators that copy game programs or disable console security measures may infringe on copyright. This is largely based on Japan's Unfair Competition Prevention Act (UCPA), which limits Nintendo's legal reach internationally.

The presentation referenced the Nintendo DS "R4" card, which allowed pirated game execution. Nintendo's successful lawsuit, involving 50 other software companies, resulted in the R4's 2009 ban in Japan under the UCPA. Nishiura also highlighted "reach apps," third-party tools (like the 3DS's "Freeshop" or the Switch's "Tinfoil") that facilitate pirated software downloads within emulators, as potential copyright violations.

Nintendo's lawsuit against Yuzu cited one million pirated copies of The Legend of Zelda: Tears of the Kingdom, alleging that Yuzu's Patreon generated $30,000 monthly through features like early access to games like Tears of the Kingdom.