Yakuza 5 Remastered

Legend mode is unlocked after completing the story once. Your first playthrough should be on Normal difficulty. On your Normal run, ensure that you get the Golden Pistol for completing all sidequests before you finish the story. Note that you have to beat the Amon fights to finish all the sidequests. You should also get the Beads of Good Fortune to reduce the number of enemy encounters on your Legend run. The Golden Pistol trivialises Legend mode. If you equip it with the Amon's Sunglasses you get from beating Amon, it will do even more damage. Every enemy and boss you fight will go down in a few hits. Bear in mind that unlike in previous Yakuza games, progress made in Premium Adventure mode (which is available after completing the story) does not carry over to New Game+, as you cannot create Clear Data in Premium Adventure. You can only make Clear Data after finishing the story in New Game. Another important thing to note is that if you want the Golden Pistol to be available to each character in their chapter of the story, you must put it in the item box with the previous character so it's available to the next character. The last opportunity to do this on each chapter is as follows:

Chapter 1 (Kiryu): Before going to the docks (where you have the brawl against a ton of Yakuza guys).
Chapter 2 (Saejima): Before going to the Winter Festival (talking to Baba in the hideout triggers this).
Chapter 3 (Haruka and Akiyama): Before going to Shin-Osaka Station where you fight Kanai and his goons as Akiyama. The fight is pretty tough without the Golden Pistol, but should be manageable if you levelled up Akiyama to at least 20 on your Normal playthrough.
Chapter 4 (Shinada): Before talking to Daigo after fighting him. After that, you will fight a bunch of enemies on the baseball field. I suggest bringing a few unbreakable weapons that you should have obtained on your Normal run with Shinada. The fight is pretty easy even without the Golden Pistol.

When you reach the Finale, be sure to equip the Golden Pistol on Kiryu as soon as possible. The Kamorucho Hills section as Kiryu will be trivial with the Golden Pistol. I thought it was pretty tough even on Normal, so I really wouldn't recommend doing it on Legend without the Golden Pistol. When you are given a choice of which character to play, always pick either Kiryu or Saejima as they are significantly stronger than Akiyama or Shinada. You will have to fight Kanai again as Akiyama without the Golden Pistol, but he should be manageable as long as you bring enough health items. The last boss will be a cakewalk for Kiryu if he has the Golden Pistol equipped.