Sonoko Kashiwagi is a yandere for the protagonist of Yandere No Onna No Ko Vol. 1.
Sonoko was a very shy girl who got picked on by her other classmates. One day, the protagonist stood up for her and scared away her tormentors. In Nagisa Nonohara and Ayase Koumoto's tracks, it's suggested that the protagonist hung out with her during and after school, which angered the two girls. In Ayase and Sonoko's tracks, Ayase was one of the people who picked on Sonoko, mostly because of her involvement with the protagonist.
Yandere Traits Edit
Sonoko is obsessed with the protagonist. She was grateful to him for sticking up for her and she became infatuated with him. She stalked him and believed that they were together despite them not interacting that much with each other. She seemed willing to let Nagisa live since she was the protagonist's younger sister. However, she seemed tempted to kill her for being nosy and trying to find him in her house. When she was confronted by Ayase one day, she killed her and turned her into fertilizer. Not long after, she went after the protagonist, believing that he betrayed her for other girls. She uses his skull as a flowerpot and regularly holds conversations with it, acting like he's still alive and that they're now together for all eternity.