Yahoo Japan Corp. is an advertising company, and it’s an e-commerce company. It’s not a gaming company.

That’s about to change.

The decision to launch Game Plus indicates that Japan’s second-most popular website really wants to make a go of this new category, further evidenced by deals signed with 52 games publishers including Square Enix Holdings Co. and Koei Tecmo Holdings Co.

As Bloomberg’s Yuji Nakamura and Yuki Furakawa wrote, Yahoo Japan now joins Facebook Inc. and Tencent Holdings Ltd. in embracing web-based games. This technology choice is important. By developing around HTML5, internet players can skirt the native platforms of Apple Inc.’s iOS and Alphabet Inc.’s Android while still delivering games on mobile and PC.

Games are a cornerstone of Apple’s mobile ecosystem, accounting for 25.1 percent of active apps in July. Business titles trail far behind, at 9.8 percent. Games tend to attract more spending, too, either for paid apps or in-app purchases.

However, a look at its most recent investor presentation indicates little interest by Yahoo Japan executives in playing games. The first mention of the topic is on page 99 of a 106-page PDF, where it’s lumped in with the…