The Japan Patent Office (JPO) did not decide in favour of Monster Energy Company in its opposition to Defensive Mark Reg. No. 5673517 for the word mark “MONSTER STRIKE” in Classes 29, 30, and 32.
[Opposition case no. 2023-900135, decided on November 4, 2025]
MONSTER STRIKE
Monster Strike, a popular mobile “slingshot hunting RPG” developed by the Japanese company Mixi, is famous for its simple pull-and-release gameplay, deep co-op mode for up to four players, frequent collaborations, and immense revenue. Monster Strike essentially saved Mixi’s social network legacy, becoming a cultural phenomenon in Japan and generating billions in revenue while fostering family communication.
Since 2014, Mixi has owned trademark registration for the word mark “MONSTER STRIKE” in Classes 9 and 41 in connection with game programs [TM Reg no. 5673517].
On March 29, 2021, Mixi filed a defensive mark application for the mark to expand the scope of protection in Classes 14, 16, 18, 21, 24, 25, 26, 28, 29, 30, 32, and 33, including beverages [TM Application no. 2021-37152].
Defensive mark
Article 64 of the Japan Trademark Law provides the requirements for defensive mark registration.
“Where a registered trademark is well known among consumers as an indicator of the designated goods or service in connection with the owner’s business and confusion is likely if the mark is to be used on dissimilar goods or services by a third party, the owner is entitled to obtain a defensive mark registration for the same mark in connection with such goods or services.”
A trademark can be registered as a defensive mark for dissimilar goods or services not covered by the original registration if the owner can demonstrate that the mark has gained significant prestige for the goods or services for which it has been used. This is because relevant consumers are likely to confuse the source of the goods or services if they are remotely associated with or dissimilar to those in the original registration due to the substantial reputation of the mark.
It is noteworthy that the JPO does not examine whether a defensive mark may confuse earlier marks that have been registered on the goods and services designated in the defensive mark application.
The JPO granted registration of the mark MONSTER STRIKLE in Classes 14, 16, 18, 21, 24, 25, 26, 28, 29, 30, 32, and 33 as a defensive mark on March 24, 2023, and published it for a post-grant opposition on April 3, 2024.
Subsequently, Monster Energy Company filed an opposition against the defensive mark registration, claiming cancellation for goods, inter alia, beverages, in Classes 29, 30, and 33, in contravention of Article 64.
JPO decision
The JPO Opposition Board found that “MONSTER STRIKE” has been widely recognised among not only consumers for game programs designated under the original registration, but also relevant consumers unrelated to the game industry.
The Board noted a trade practice that, in general, there are a lot of goods, including food and beverages, distributed bearing well-known contents and characters in collaboration with other suppliers. Bearing this in mind, it is reasonable to find that the contested goods are to some extent associated with the goods and services in the original registration.
Therefore, where the contested goods bearing the term “MONSTER STRIKE” are placed in the market by a third party, relevant consumers are likely to consider that the goods originate from Mixi or economically linked undertakings, and thus confuse the source accordingly.
The opponent claimed their substantial use of the mark “MONSTER” on the energy drink. However, such facts are irrelevant to evaluate the likelihood of confusion stipulated under Article 64(1).
Based on the above findings, the JPO dismissed the opposition and declared registration of the defensive mark as the status quo.