Yes, it is. The fact that it's based on a true story gives it an extra layer of authenticity. The characters seem more real and the events are often more impactful because they actually happened.
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.
Well, another option could be Hulu. Sometimes they also feature movies that are based on real events. However, it really depends on the licensing agreements that these platforms have. If it's a relatively unknown movie, you might also want to check out some independent movie streaming services or local video rental stores that might carry it.