The Picture Source: Yumemigachi
In the novel, Nibutani isn't the idol of the class, but rather, Yuuta's class men rated it to Kazari Kannagi as the most beautiful woman of class, and whose beauty has exceeded all the girls in her school. Kannagi's the true class idol.
The personality of Kannagi-san seeing it from an outside perspective; is cheerful, an active girl, jokester. But deep down, has a strong character and a clear example is when her boyfriend tried to kiss him. This girl is very voluptuous and dark. I still remember the ghosts that have this girl (is the identification of evil) and what would be able to make me if i am too greedy with her body. She will have many fans (if the animation studio knows how to use the character) their content is interesting, the pun with her name makes me think that this girl is God.
Shichimiya, Nibutani and Kannagi are the characters that is worth reading the novel (Curiosity).