Yuka Mochida

Despite being a teenager, Yuka acts in a much younger manner than her age due to her being pampered by her parents. She tries to act like an adult in order to be taken more seriously by her peers, but her constant failures at doing so cause her to come across as even more immature. Her naivety makes her childlike innocence more apparent than most others trapped in Heavenly Host Elementary School, but it also makes her susceptible to being manipulated by the school's more ill-intentioned residents (humans and ghosts alike). It also makes her more psychologically vulnerable to the horrors of the school, causing her to easily break down at the sight of blood, violence, and death. Because she is spoiled, she depends on those older and more mature than she is to make decisions for her. However, her experiences throughout Heavenly Host force her to act more on her own decisions.

(Source: Corpse Party Wikia)