Also known as: アオイシロ
"The Blue Castle"
A Yuri visual novel by Success, from the same line as Akai Ito. The story follows Osanai Shouko, captain of the kendo team at a girl's high school on a summer training camp. The plot is heavy on back story and explanations of folklore.
A version for the Playstation 2 came first, followed by a PC release. No erotic scenes or CG were added, though.