Sai Jounouchi, known as the "Ice Machine," started playing Angelic Layer at the request of her terminally ill sister Rin. Rin designed what the angel would look like, but died before Sai could create her. As a result, Sai states that her reason for playing Angelic Layer is "to become strong." Sai is from Kanagawa Prefecture and was the runner-up in the Kantō Regional games in the past year. She is friends with Kaede, who went to the same middle school as Sai. Her angel is Shirahime.