Have you ever wanted to upload a character from your favorite anime-style game, only for it to get shading artifacts on the face like this,



when you were imagining it to look like this?



If so, follow these few simple steps to improve the looks of your model almost instantly.

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Update 4/19/22: Also added a more advanced method that results in more accurate shading, but with the risk of having a slight amount of artifacts.


Simple method: noticeable unnatural shadow gradient on lower portion of face


Advanced method: proper shading on lower portion of face

• Blender 2.8 or above
  
• An anime-style model that isn't shading well
  
• Very rudimentary knowledge of Blender

Advanced method:

• Slightly less rudimentary knowledge of Blender

In Edit Mode, select the face of the model, like so, and press S to separate that part of the mesh into a separate object.



Next, select the new face object (in Object Mode), and apply a Normal Edit modifier.



Then, go to the Object Data Properties menu (upside-down triangle on the right-side menu), and enable Auto-Smooth under the Normals tab.



(The Normal Edit modifier will prompt you to enable this once added, if it's not enabled already).

Set the modifier to "Radial" if it isn't set to it by default.


Add a new object using the Add menu to use as a target for the modifier. This can theoretically be any object (as the location of the object is the only thing that matters here), but I would recommend using an Empty for visibility and convenience. I used "Plain Axes" here, but you can also use "Sphere" if it helps for visualization.



Next, click the eyedropper on the Normal Edit modifier, and set the newly added object (the Empty) as the target.



Once you set the target for the Normal Edit modifier, the shading on the face should start looking strange, like so:




Next, you'll want to move the target object around until shading artifacts are gone. This is generally achieved by placing the target behind the face, at around the center of the head. Make sure the target isn't too low or too high, which can cause strange shading in areas like the brow, or weird gradations at the upper or lower parts of the face.

A proper result should look like so:




Once you're done making adjustments, you'll want to apply the Normal Edit modifier, which can be done by clicking on the down arrow on the right side of the modifier name and clicking "Apply"



After the modifier is applied, select the face in object mode, shift-click to also select the rest of the body, and press Ctrl-J to join the two parts of the model together.



After this, you're free to delete the object you used as a target for the Normal Edit modifier, and, provided the model is otherwise properly set up, you should be able to export it for use in-game.

The advanced method is similar to the previous method, but we'll be transferring normals to the face via a custom mesh, rather than just using radial normals.

Same as the previous method; detach the face into a separate object, and enable Auto Smooth for the face object.

This step is optional, but will help in visualizing how the normals of the face will look. Set the viewport shading mode to "Solid", and enable the appropriate matcap:



This step heavily depends on how you want the model to be shaded, but the simplest method would likely be to create a half-cylinder and morph it roughly in the shape of the face. Make sure the half-cylinder is smooth to prevent artifacts (bevel your edges + apply subdivisions; applying smooth shading likely helps as well). If your separated face object also includes the underside of the chin and jawbone, ensure this is reflected in the mesh as well.



For visibility purposes, you may want to set the half-cylinder's display mode to wireframe via the object properties panel.



Next, apply a Data Transfer modifier to the face object and set the target to the mesh you just created. Check "Face Corner Data" and then select "Custom Normals". Experiment with the "Mapping" option to see which one provides the best results; in my case, this was "Nearest Corner of Nearest Face".



Once the Data Transfer modifier is set up properly, you can apply the modifier and join the face object back to the rest of the mesh. Once the modifier's applied, you can also delete the custom mesh you created. If everything else is set up properly, you can now export the mesh for use in-game.