Chika Koizumi

Chika is the childhood friend of Ryōta and in their romantic relationship with each other, she often takes the lead role. She has a crush on him and despite her best attempts, she is unable to get Ryōta to notice. She is fond of her childhood memories that she shares with Ryōta. She is very level-headed and has an unyielding spirit, unafraid to play pranks on Ryōta, no matter what position they leave him in, and physically abusing Ryōta should he deserve it. Her number on the class list is 10.

(Source: Wikipedia)