This mod was made to replace Maru's portrait and character sprite files. I'd recommend backing the original files up in case you want to remove these sprite edits, as not doing so can make it it a little annoying to replace the original sprites (for steam, just verify integrity of game files in the game's property's, which will replace all modified files with the originals). Not 100% necessary to do, but helpful.
 
Instructions:

- Unzip or extract files.

- Place into the Stardew Valley folder under Content\Portraits and Content\Characters respectively.