Shimizu, Kiyoko

A mostly quiet girl in the beginning, she is shown to be serious and passionate about her position as team manager as when she along with the other third years were reluctant to step down from the club. She cares a lot about the members of the team, as shown when she washed and fixed up Karasuno's old banner from back when they were strong to increase the players' morale.

Suga has stated that Kiyoko is not one to show her feelings often (fixing the banner is unusual for her) but after Yachi joins the team, Kiyoko opens up and shows a lot more emotions, smiling often and even cracking jokes to let Yachi ease up.

(Source: Haikyuu!! Wiki)