How to get darker shadow when a character inside another object's shadow?

In my scene, I’m using AmbientLight and DirectionalLight. As you can see in the images, there are trees and a character. Trees have big shadows, also my character casts shadow as well. The thing I want is, when my character inside the shadow of a tree, it casts darker shadow of itself to the ground. For the ground, I’m using PlaneGeometry and MeshStandardMaterial.

I need characters shadow (darker) in here as well;

I need something like this: