Everyone please do remember that this is not only applied in Twitter or merely Japan, it exists everywhere. The sheer mob mentality of the mindless toxic masses always gather together to shame people under the veil of anonymity since that they have too much free time on their hand.
Again, this is not limited to celebrities either. Cyberbullying can be big or small and it will always hurt the other people, even if the posters are sheer nobodies, words can still hurt someone's psyche when done in a large scale.
Unless you're shielding Trump, badum-tst