Yakuza games use 2 different models for major characters, one for gameplay, with lower quality textures, and one for cutscenes, with higher quality textures. This mod basically merges cutscenes textures with gameplay models.

In general face textures and tattoos are improved for the major characters.
Textures themselves are 4 times bigger. They're taken straight from the game, so there should be no issues with inconsistent art style of textures, since they were made by the original game devs.

See pictures for comparison.

Installation (easy way):
Download "Packaged" version, extract the file and copy the "data" folder over to game's folder, usually something like "C:\Program Files\Steam\steamapps\common\Yakuza 6 - The Song of Life"

Installation (Parless way):
Install using Ryu Mod Manager by SutandoTsukai181 https://github.com/SutandoTsukai181/RyuModManager/releases/latest
1. Extract "HighResChara_textures" into "mods" folder in your Y6 folder.
2. Add "HighResChara_textures" into your ModLoadOrder.txt
3. Run RyuModManager

Installation (manual way):
Download "DIY" version and use the ParTool with "add" attribute.
Example installation:
Extract the archive and copy the "chara" folder into Yakuza 6 folder\data.
Copy the ParTool.exe into Yakuza 6 folder\data. (download https://github.com/Kaplas80/ParManager/releases/latest )
In Yakuza 6 folder\data create .bat file with contents "ParTool add chara.par chara chara1.par -c 0" or "ParTool add chara.par chara chara1.par -c 1", if you want compression, and launch it.
Rename "chara.par" into "chara.par.bak", and rename "chara1.par" into "chara.par"

---

On top of that, you can use Solidical's mod to force cutscene models for Kiryu in gameplay, which is available on Yakuza Modding Community Discord.