Toge Inumaki is important too. His special cursed speech ability makes him stand out. Also, the principal of the school, Masamichi Yaga, is likely to be important as he is in a position of authority and has an influence on Gojo and the other students. There could be other characters like the members of different clans that also play roles in the complex web of the story.
The Sachiko Japanese ghost story is often a chilling tale. Usually, it involves elements like an eerie presence. Sachiko might be a spirit with a tragic past that haunts a particular place. In many Japanese ghost stories, there are often themes of vengeance or unresolved issues from the spirit's past life. However, there are different versions of the Sachiko story, some might focus on a specific location she haunts, like an old house or a forest.
One common element is the sense of a tragic past. Sachiko is likely to have had a difficult or unfair life that led to her becoming a ghost. Another element is the idea of a haunting. This means she is associated with a particular place, like an old building or a dark alley. Fear is also a big part of it. People in the story are usually scared of Sachiko's presence, whether it's through seeing her or just feeling her 'energy'.