℃-ute Official Book "9gatsu 10ka wa ℃-ute no Hi" (℃-ute Official Book『9月10日は℃-uteの日』) is the first official book by ℃-ute. It was released on September 10, 2013, also known as ℃-ute no Hi (℃-ute Day). The book includes 100 Q&As, solo projects planned by each member, long interviews, a five-member talk about ℃-ute's history, photos from the Hello! Project Kids era, offshots by Nakajima Saki, handwritten messages to the members, and gravure.