December 2018 is the 59th month of the PlayStation 4 being on sale in Japan. The gap grew in favor of the PlayStation 4 by 106,776 units in the last month and in favor of the PlayStation 4 by 235,868 units in the last 12 months. The PlayStation 4 currently leads by just 440,458 units.
The PlayStation 3 launched in November 2006, while the PlayStation 4 launched in February 2014. The PlayStation 4 has sold 7.58 million units, while its predecessor the PlayStation 3 sold 7.14 million units.