Sega Files ¥1 Billion Patent Lawsuit Against Memento Mori Developer Bank of Innovation

Sega Corporation has taken significant legal action against Japanese developer Bank of Innovation, best known for the idle mobile RPG Memento Mori, alleging multiple patent infringements.

This move, which underscores growing tensions over intellectual property in Japan's lucrative mobile gaming sector, seeks damages totaling ¥1 billion (approximately USD $6.63 million) and demands an injunction against Memento Mori and other connected content. According to reports from Gamesindustry.biz and sources at the Otaku Research Institute, Sega—world-renowned for iconic franchises like Sonic the Hedgehog—is targeting Bank of Innovation over several of its mobile RPG titles.

Talks between the companies had been underway, but negotiations reportedly fell through without resolution.

Despite the lawsuit, Bank of Innovation firmly denies any wrongdoing and has publicly committed to defending itself in court while continuing normal operations for Memento Mori. Since the suit was announced, Bank of Innovation's stock has dropped precipitously, falling close to 18% in a single day.

The legal complaint cites five specific patents registered in Japan: 5930111, 6402953, 6891987, 7297361, and 7411307.

Coverage by Automaton Media highlights that all these patents pertain to core gacha game mechanics widely used in the mobile game industry.

Industry analyst Serkan Toto notes that at least one of the contested patents is related to the oft-used character card fusion feature, a staple element in many collectible RPGs. Memento Mori debuted on iOS and Android platforms in 2022 and garnered attention for its striking art direction and exceptional soundtrack, featuring live performances and original songs composed and performed by renowned Japanese artists.

The game centers on Witches—girls with unique powers—who are on the run from a ruthless Inquisition.

Players step into the role of a Lord helping these characters, with gameplay designed around accessible, idle mechanics typical of AFK mobile RPGs. Sega's aggressive legal stance has stirred widespread industry attention, especially as it puts a spotlight on patent protections surrounding gacha systems, which are foundational to the business model of countless free-to-play mobile games.

It also follows The Pokémon Company's recent legal action against Pocketpair, the creators of Palworld, signaling a broader trend of major Japanese gaming firms enforcing their patents in court. As the lawsuit unfolds, the outcome could influence not only future development strategies for mobile gaming companies operating in Japan but also the evolution of gacha-based monetization models globally.

Sega patent mobile Bank of Innovation Memento Mori iOS Android Automaton Media Gamesindustry.biz Serkan Toto The Pokémon Company Pocketpair