Japan's App Store Law: What Mobile Game Studios Plan

Japan's app store law for mobile games, formally the Mobile Software Competition Act, takes full effect in December, and reporting suggests Apple and Google are now firming up how they intend to comply. Neither has published a complete final specification. For a mobile game studio earning meaningful revenue in Japan, the shape of that compliance will matter more to Japan-specific revenue than almost any single UA decision made this quarter. Alternative billing options, third-party store access, something narrower: the form it takes is the open question.

What Japan's app store law actually requires

Japan's Mobile Software Competition Act, passed to address concerns about the market power Apple and Google hold over app distribution and payments in Japan, sits close in intent to the European Union's Digital Markets Act and to the injunctions running through the Epic v Apple and Epic v Google cases in the United States. It aims to open the door to alternative app stores and alternative payment methods on both platforms' Japanese storefronts, reducing the exclusivity that has let both companies set commission rates without competitive pressure from within their own ecosystems.

Apple and Google are still working out the exact mechanics they will offer under the law, and compliance plans keep developing ahead of the December deadline. Treat any specific commission percentages or technical details circulating now as provisional. What is reasonably safe to plan around is the direction: Japan is very likely to gain some version of the alternative billing and distribution flexibility that US developers gained through 2024's link-out rulings and that EU developers have had since the Digital Markets Act took effect in March 2024.

Why this matters more for games than most categories

Mobile games are disproportionately exposed to platform commission rates compared to most other app categories, because in-app purchases make up such a large share of games revenue relative to the subscription or one-time-purchase models common elsewhere. Japan is one of the largest single mobile games markets globally. Even a partial reduction in effective commission rates, achieved through alternative billing options that let a studio route some transactions outside the platform's own payment system, could represent a meaningful margin improvement for any studio with substantial Japanese revenue.

As we set out in Apple's Core Technology Commission and the 5% math, a headline commission cut rarely arrives without some offsetting structure attached, and studios modelling Japan should apply the same scepticism.

The EU and US experience offers a caution as much as an opportunity. Alternative billing in both markets has come with friction of its own: consent flows, disclosure requirements, sometimes fees that partially offset the commission savings, such as Apple's per-install Core Technology Fee model in the EU. A studio assuming Japan will deliver a clean commission reduction without any offsetting structure is planning against the optimistic end of a range that has not, in other markets, played out that simply.

What to plan now, without final rules

Studios don't need to wait for the final compliance specifications to start useful preparation. Several pieces of groundwork apply regardless of the exact mechanics Apple and Google land on.

Attribution and measurement setups need to handle a second payment path if alternative billing does arrive, in the same way MMPs had to build new tracking flows for US web-shop and alternative billing traffic through 2025. Wait for the rules to be final before starting that technical scoping and the timeline compresses badly once the December deadline firms up.

Finance and legal teams should model a range of commission scenarios now, from a modest reduction with offsetting fees to a more substantial one, rather than a single assumed outcome, so that pricing and promotional planning for the Japanese market does not rest on one guess about where the final rules land.

UA teams specifically should treat this as a measurement and infrastructure question well before it becomes a media-buying one. Any shift in how revenue attributes back to campaigns, particularly if a share of transactions moves outside the platform's own IAP system, changes ROAS calculations for Japan-specific campaigns. Model those changes before the first affected cohort arrives rather than reconstructing them afterward.

What the EU rollout suggests about the transition period

The EU's experience under the Digital Markets Act, in force since March 2024, is the closest comparable case studios have to work from. The detail worth carrying over is not how fast the rules technically allowed change. It is how gradual actual adoption was. Alternative billing options existed on paper well before most publishers had built the technical and consent flows needed to route transactions through them, and uptake among mobile game titles specifically lagged uptake in other app categories with simpler purchase flows. A studio expecting Japan's alternative billing options to shift a large share of revenue immediately after the December deadline should weight that expectation against how slowly the equivalent EU shift actually played out, rather than against the theoretical maximum the rules permit.

That gradual pattern is not necessarily a reason to delay preparation. If anything, it argues for treating the December deadline as the start of a testing and validation period rather than a single cutover date, and for building the internal case to leadership on that basis: early adoption will likely be partial, measurement needs to be ready for it regardless, and the studios that have their tracking and consent flows validated before volume ramps will sit in a better position to capture whatever share of transactions does move.

A short readiness checklist

• Confirm with your MMP whether Japan-specific alternative billing tracking is on their near-term roadmap, given the precedent set by their US and EU work through 2025.
• Model at least two commission scenarios for Japan, one with meaningful offsetting fees and one without, rather than planning finance projections around a single assumed outcome.
• Flag Japan-specific campaigns for a dedicated measurement review once compliance details firm up, since attribution logic may need updates ahead of the December enforcement date.
• Watch how EU and US alternative billing adoption rates among comparable titles have actually played out, since real uptake data from those markets is a better planning input than assumptions about Japan's rules alone.
• Assign clear ownership, ideally spanning legal, finance and measurement, for tracking compliance announcements as they firm up through the autumn, rather than leaving it to whichever team notices first.

December's enforcement date gives studios a defined runway, not an open-ended one. Apple's and Google's compliance plans will keep firming up between now and then. The direction is clear enough that the preparation work does not need to wait for the final document to land.

Related archive reading

These articles provide related context and remain subject to their stated review status.

• Japan Smartphone Act App Stores: What Opens for Buyers
• Dark patterns, consumer law and UA