The final game of the Yakuza Remastered Collection, Yakuza 5 has unlocked today on PS4 and with that every Yakuza game in the main series from Yakuza 0 - Song of Life is now available on PS4 and I highly recommend these games.
The fighting system never gets old and it's so easy to spend hours upon hours just running around doing all the side activities. Even if you don't do the side activities the stories are pretty great as well.
Yakuza 3, 4 and 5 can be purchased separately for $19.99 each or can be bought in a bundle for $59.99. There is also a physical Day One edition of the bundle which includes Yakuza 3 and 4 on one PS4 disc and Yakuza 5 on a single disc. It also comes with a Steelbook case and a special PS3 case for Yakuza 5 (game not included)