Daitoshokan no Hitsujikai: Houkago Shippo Days

The story follows the protagonist Kei Kirishima and his childhood friend Nozomi Toki who are part of the Cat Photography Club where they take pictures of the cats who have set up a nest close to the school. The two of them, along with Sakuya Fujimiya grew up together on the countryside before they moved to the city to study, but since Sakuya was too young and her mother had forbidden her from leaving, she had to stay behind.

One day Kei's doorbell rings... It's Sakuya and she has ran away from home.