Aoi doesn’t go to school; instead he works hard every day on part-time jobs to care for his two imoutos, Hina and Runa. While he does have some regrets about not attending school, he is satisfied and motivated by the sight of his imoutos’ smiles.
One winter day, Aoi was working harder than usual in order to celebrate his imoutos’ birthday, which was fast approaching. Then he reunited with his former kouhai Minori and met his shy neighbour Koyuki. These encounters brought about changes in Aoi’s relationship with his imoutos.