The twins, Aoi and Akane, have been living with their grandparents from their late mother's side and their father. They are now fifth graders and are about to start taking steps towards life while embracing new encounters and new experiences on their own.

From Which Scanlations:

Shiharu is a high-school student who loves kids, lives in an orphanage, and works at a daycare... Until the handsome uncle of two-year-old twins offers her a raise if she'll be their babysitter. Often relying on memories of her mother's actions for guidance, Shiharu quickly finds herself falling in love with her new makeshift family.