The fact that they are based on true stories makes them scarier because it gives a sense of realism. We know that these things could potentially happen in real life.
There's also 'Shiki'. This anime is based on the concept of vampires, which has some roots in real - world superstitions and stories. It shows a small village being invaded by these mysterious beings. The slow - burn horror and the psychological aspects of the characters make it a great horror anime. It delves deep into themes like fear, paranoia, and the human condition in the face of the unknown.
It varies. Some horror stories draw from real-life tragedies or mysterious phenomena, but a large portion are crafted from the minds of writers seeking to evoke fear through fictional scenarios.
Definitely not. Monster is a purely fictional anime that showcases the imagination and creativity of its creators. It doesn't draw from real-life events or people.
Another example could be 'A Silent Voice'. While not a direct retelling of a specific true event, it touches on real-life issues like bullying and redemption in a very relatable way.