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 last person to succeed the throne was the Qing Emperor's Third Prince, Li Chengping. After the Qing Emperor was killed by Fan Xian and Wu Zhu, the Qing Kingdom had no suitable candidate to inherit the throne. In the end, the ministers of the Qing Kingdom elected Li Chengping as the new Emperor, and the Third Prince became the new Emperor.
The last person to succeed the throne was the Qing Emperor's Third Prince, Li Chengping. After the Qing Emperor was killed by Fan Xian and Wu Zhu, the Qing officials elected Li Chengping as the new Emperor.