Since its launch in Japan in February this year, Sony’s (NYSE:SNE) PlayStation 4 has experienced lackluster sales in the country. Though the eighth-generation console has been available for around five months in Japan, only 620,000 units have moved off shelves. Why isn’t the popular console selling better?

According to Sony Group President and CEO Andrew House, Japanese publishers and developers were reluctant to support the PS4 ahead of its launch. House told Eurogamer last week that developers in Japan were nervous about making games for a new platform and remained comfortable with creating titles for the PlayStation 3.

"We're conscious of the fact we have not had yet the sort of groundswell of Japan native content from Japanese publishers and developers," House explained. "I view that as temporary.

"There's definite developer and publisher enthusiasm for the platform, especially having seen the overarching success it's had in markets outside of Japan, and again this outpacing of the PlayStation 2. We'll see that come into games people in Japan will get excited about, but unfortunately a little bit later than has happened in other markets."

Unlike in Western countries, Japanese game sales show that consumers of electronic entertainment in the region are more interested in the previous generation of video games. Earlier this month, Japan’s best-selling PS4 game was Ubisoft’s open world, action-adventure title “Watch Dogs,” which moved 65,000 copies. However, data consistently shows that PlayStation 3 games continue to sell well in the island nation, and the PlayStation 3 version of the same title sold 40,000 copies.

"For whatever reasons, when we were evangelizing around the platform, we were having a tougher sell with Japanese publishers and developers," House continued.

"There was a comfort level around PS3 that was playing into that. There was a slight level of concern around the viability of the console market in Japan. But we've really turned a corner on that and demonstrated that if you're a publisher that wants to reach a global market with good and immersive games then the PS4 is definitely the place to be."

In other areas of the world, like North America and Europe, the PS4 continues to outshine the Xbox One, at 9 million units sold to 5 million consoles sold.  Both consoles launched last November, but the PlayStation 4 has beaten Microsoft’s device every month since their launches.

"Hats off to Sony, they've had a great start; they have been in more countries and – to date, at least – at a lower price. We have announced a new Xbox One at a lower price; we go to 29 new countries starting in September,” Microsoft Corporate Vice President Phil Harrison told Edge magazine last week.

The Xbox One will reach buyers in Japan in September, along with 29 titles, such as "Forza Motorsport 2," "Killer Instinct," "Wolfenstein: The New Order," "Battlefield 4" and "FIFA 14." Will Microsoft's console see better sales figures? Only time will tell.