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.
Leisure books usually referred to books for entertainment and had nothing to do with the main occupation. It could include novels, such as entertainment novels. However, not all leisure books were novels, because leisure books could also include other types of books, such as essays, magazines, and so on. Therefore, it could be said that leisure books could be novels, but not all leisure books were novels.
There are a few novels about idle princes that I can recommend. Among them were The Tang Dynasty's Unemployed Prince and The Unemployed Prince of Emotions and Desires. " The Unemployed Prince of the Tang Dynasty " was a story about a modern teacher who traveled to the prosperous Zhenguan period of the Tang Dynasty. He wanted to be an idle prince. On the other hand," The Unbusy Prince of Emotions and Desires " was an ancient novel about revenge, jokes, and playing the pig to eat the tiger. These novels all had different plots and story backgrounds, suitable for readers who liked to read about idle princes.