[hyl]

Warning: actual route spoilers this time.

Spoiler for spoilers for Chisato in Isara's story:

Chisato became extremely jealous of Isara, because Oojima obviously fell for Isara in that route. When Yuuki decided that they should focus their elections to fight the discrmination problem, Chisato decided to drop out of the team because she was questioning if he was doing the elections for the sake of the club or rather for Isara. Because of this internal conflict started by her, other members (first starting with Mifuyu, then the 2 monkeys ) also decided to leave the team. Due to other problems and misunderstandings at one point, only Isara and Yuuki were left for the elections. Making the situation seem hopeless.
Even after most of the members rekindled later on, Chisato still insisted being stubborn and angry at Isara. Chisto started to act more normal after Isara got hit by a car, because of Chisato's recklessness.

Spoiler for Chisato in Mifuyu's story:

While i don't like Chisato in this story, it was mostly the fault of Mifuyu as well. Near the end of the route Chisato knew that Mifuyu and Yuuki were hiding their relation and she lashed out at Mifuyu for stealing Yuuki away from her. Causing Mifuyu to run away while it was raining, which may or may not be the reason for the extra drama at the end when Mifuyu ended up in the hospital because of her weaker consititution.