I imported 3D models that was ripped from game file(model-resource), but it has black things around eyes and mouth why is this happening?
Model file is from The Model's Resource, Nintendo model archive

*Edited after seeing comments(thanks!)
I saw your comment and reply, and watched some videos about bsdf, still I got a problem as you can see my pictures below. I somehow erased the shadows, but the eyes became too tranparent and also are looking weird.
I only changed the eyes, not the mouth at all. so the question is on eyes, at this point.

with opaque mode

with alpha blend mode

when bitmap connected to alpha is muted(opaque)

when bitmap connected to alpha is muted(opaque)

in render mode with opaque mode
**Solved, Thank you so much! :D
It seems to be a case of transparent parts rendered as black (this is not a bug, but a feature in material view)

You are in material-view mode and not render mode. When you go into render-mode it should appear correct (if nodes are setup properly).

If nodes are incorrect, It normally is the following:

Its possibly that the alpha output of the image-texture is not connected to the alpha of your principled bsdf.
Edit: As I suspected, the nodes are not properly setup. All you have to do is connect the 'Alpha' output from image texture to 'Alpha' input of Principled BSDF
Note: in the first image below, on the right side, it mistyped &quot;Rendered View&quot;. I meant to say 'Material View/Viewport Shading mode'. Its a small mistake, I noticed late.