Doctor M: Dark Angel IV

A child is left behind by his mother in a department store restaurant, carrying Miwako's contact information and a photo of a man named Ryuju, an old acquaintance of Miwako's... Where is the mother? Why did she entrust the child to Miwako? And what is the relationship between the child and Ryuju...?! Miwako becomes the guardian of the child, Rio, and begins traveling around the country in search of clues...! A new chapter begins in the story of the solitary genius surgeon, Hikawa Miwako! (Source: Akita Shoten, translated)