|First Appearance||Alliance of the Golden Witch|
|Portrayed By||Akihiko Ishizumi|
Nanjo's son. Inherited the Nanjo Clinic. Unlike Nanjo, he seems to be a more sobered, indifferent person.
After the rampage surrounding Rokkenjima, he grew to completely despise the press, and he never spoke again of what happened around that time.
He once had a daughter afflicted with an incurable disease, but unfortunately, she wasn't able to live out her natural lifespan.
Masayuki appears as a middle-aged man with black eyes and grey hair. He typically wears a physician's coat over a white shirt and green tie.
Masayuki is jaded in matters concerning the Rokkenjima massacre and the death of his father due to the countless interviews that have been proposed to him.
Alliance of the Golden witch
In 1998, Ange goes to interview relatives of people who died in the Rokkenjima Massacre, with her first stop being Masayuki. Masayuki reveals that, some time after the Massacre, he had received a letter containing a PIN number, a bank card, and a set of keys to a safe-deposit box; this letter was arranged such that it listed Terumasa as the sender and went to an address that didn't exist, thereby causing the postal service to return the letter to its home address.
After investigating these items, Masayuki was presented with a case containing a massive amount of money. Masayuki rejected this money, finding it to be very suspicious. Ange compares the handwriting on the letter to that in Maria's grimoire and starts to piece something together.
- Masayuki shares a VA with his father, Terumasa Nanjo.