is the sweet-natured younger sister of Kotonoha. Unlike her older sibling, Kokoro is peppy, talkative and full of curiosity, and although she frequently teases Kotonoha, she worries about her greatly. She has a good friend named Uzuki and affectionately looks up to Makoto as her older brother. Kokoro lives with Kotonoha and their mother Manami and father. Her birthday and his surname are derived from Katsura Taro.