From MangaHelpers:
At the scene of a terrible murder, only Todo is able to find the surviving little girl in the closet--his niece Tsubasa. Four years later, Todo and his father are caring for Tsubasa, who no longer speaks, and Todo continues to work as a police detective. He's assigned to a new partner, a young woman with a promising future, Saeki. As Todo and Saeki team up to solve murder cases together, they will also both have to confront their own painful pasts.