Yakuza‘s prequel story is told in Yakuza 0. In Japan, it launched in March for the PlayStation 4 and PlayStation 3 – over there, the veteran console is still selling nicely ,and this is why the Sony platform games tend to be multiplatform. Yakuza 0 was confirmed to have a localized release in North America for the PS4, but there was no release date mentioned. (They also didn’t say whether the game will be available in Europe or not – that is weird.)
However, the Canadian PlayStation blog might have leaked a target launch window of Yakuza 0. They wrote 2017. While it’s a one-year improvement after 5 (Japanese release date: 2012 December, NA/EU launch three years after), but it’d still be a two-year difference. This is quite a lot nowadays. We didn’t even think of Yakuza 6‘s situation yet! It’s going to be out in Japan in late 2016 exclusively for the PS4 – although there’s no word on localization, when would it even be available in English?