We often consider pets as an important part of our lives. Many pet owners share their pets' daily lives with other friends and family members through social media. However, there is no social media yet for sharing stories with other pets and for their lives, such as "Facebook." We are talking about pets through various social media. However, the whole story is still made up of online users. "Petbook" is a social media for pet-centered design. It provides spaces for pets to share their stories. Pet owners' role is required to deliver a characteristic of their pet when they talk about stories representing their pets. Thus, "Petbook" would bring a potential social network as a new online communication method between pet owners.