Save 25 - Just talk to the Dead-Eyed man in Mukurogai and turn the Worn Magical Katana and the achievement will pop up
Save 26 - At Kiyomizu Temple, just open the door and fight him.
Save 27 - Beat the last dungeon for Sanada Takedown achievement and grind few weak dungeon for Diligence Records achievement

Save location :
After downloading the folder, unzip it using 7zip or winrar, inside is a folder called Like A Dragon Ishin Saves open the folder and copy the files, this part is different from most the other Yakuza games so pay attention, you may need to make hidden folders/files appear in windows to find this folder, if you do not know how to do this, search on google for a guide.
To find the folder go to your taskbar and type in %appdata% a folder called roaming will appear, from there go to roaming\Sega\Likeadragonishin\ <user-id> \ and paste your saves there.
I really recommend backing up your own saves, just in case. You might need to turn off steam cloud for Like a Dragon: Ishin! for this to work, to do that, right click on Like a Dragon: Ishin! in your library and go to properties and you will see a tickbox under steam cloud in general.