Trying to get my character darker once passing through a shadow

What's the easiest way to accomplish this?

 

The easiest? Just change it´s color:

Code (CSharp):

1.  SpriteRenderer renderer = GetComponent<SpriteRenderer>();
2.   renderer.color = new Color(r, g, b, alpha);
3. //or renderer.color  =  black; //Too dark?

Edit:
Oh and even better and easier, take the tree sprite and slice it into 2 different spritres (shadow and tree), set the shadow sorting layer over player´s sorting layer and enemies, you will get better results.
The shadow has to have some alpha transparency (just in case)

 

@jc-drile77 Pure Genius! That was so simple haha. Thanks a bunch!

 

No problem !
The game is looking great

 

@jc-drile77 Thanks!