Yakuza 5 Remastered

You can start this Side Story in Part 4, Chapter 2. There are 7 main missions, and you need to complete all of them, the last one being "The Final Dual", where you need to hit 5 super fast pitches out of 10. Hit to utilize Heat Eye if you need to.

If you're struggling at winning, you can practice the batting minigame, purchase batting equipment from Ebisu Pawn and the two online stores, or train with Coach Iragashi.

Some of the trainings seem daunting if you're not good at the minigames, but if you know what you're doing, they're not that bad (maybe catching the marlin).

Tips:
Karaoke: Play Rouge on Love on casual. It's very easy to get 800 points.
Catch the Marlin: Use shrimp, Prawn, or Lobster, and try to cast out to 132-138 meters (I caught it at 138 meters). Hit when you see the prompt, then hold and the entire time while holding when the meter turns red. You know it's a marlin if the meter bounces all over the place. Once I almost lost it when the meter went purple despite holding to give it slack.

Here's a video that shows someone catching a marlin:

NOTE: This video is NOT mine.

Check out CyricZ's guide for information on how to complete the trainings (NOTE: I can personally confirm Machine Gun Kiss is NOT needed for the Karaoke training.)
https://gamefaqs.gamespot.com/ps4/239457-yakuza-5-remastered...

Check out CyricZ's guide on how to complete the side story:
https://gamefaqs.gamespot.com/ps4/239457-yakuza-5-remastered...