- Overhauled localization
- All content restored
- 60 fps, 1080P gameplay
- English Karaoke lyrics
- Substory Markers
Apparently, you can buy them altogether now, and a packaged version will be available after Y5 comes out.
Speaking from experience, it will take you months to get through them if you play Y3-5 back-to-back-to-back, so don't hesitate to get started now, lol. Either way, all of the numbered games are officially available on the PS4. :D
Also as a sidenote, apparently Ishin is "under consideration" to be localized as well.