Uikawa Shino / 羽衣川 詩乃 - Niizuma Koyomi & Niizuma Shino

She is the second daughter of the head of the Uikawa-style tea ceremony school and also Soushirou's older childhood friend.
She has come to countryside where he now lives to be his wife, back in the day he use to call her "nee-sama" and she still strongly wishes to watch over him as his "nee-sama".