Beats me, I ain't a lawyer. I was just saying that someone tried that and got in big trouble
Actually, you can do it, you can modify the cg as long as you don't make money from it and you are willing to delete it if Takeda personally asks you, not because it is a crime but out of respect for the author who doesn't like what you do.
Can you do this if you live in Japan? Yes, as long as it is for your own use.
can you do this outside of Japan? Yes, because Japanese laws do not apply to you.
can an author bother for modifying his work? Yes and it is your duty to respect their wishes and delete it and apologize if he asks you for using it without his permission.
but are you committing a crime? not as long as you don't make money.