Senichiya no Kagi

From Shoujo Magic: This is a three volume collection of stories by the world renowned mangaka, Chiho Saito. English audiences may know her best for Utena, though Utena really is not representative of her manga. The stories in 1001 Keys are Love Stories between different people. They range in their maturity levels, but they are published in a more mature Shoujo manga. The one common element between all of the stories is the presence of a black and white cat named Chu - Chu (Kiss - Kiss).