Nobunaga's Portrait: a drawing or a picture?

I got the hint for this post from the usual Otsuke's, when in one of his post casually said that probably the famous portrait of Nobunaga by the hand of Giovanni Niccolò wasn't a portrait of Nobunaga but a picture of one of his relatives taken in the Meiji era.

Shock ensued.
The chance that the portrait that made us fangirls whimper with historical satisfaction wasn't really Nobunaga.
So today I opened my internet and decided to indagate the issue.

First of all, the fact that the portrait is not an actual portrait of the real Nobunaga is a fact.
The artwork is dated after 1583, when Nobunaga was long dead, as our Jesuit painter reached Macao only in 1582.
According to the original story, the portrait was done by following the description of some relative of Nobunaga, from the Oda Clan managed by his son Nobukatsu.
It goes like this: getting to know about the skills of this Jesuit Italian painter and the novelty that he represented, Nobukatsu commissioned him a portrait of his illustrious predecessor after his death, and Niccolò (also rendered as "Nicolao" because LOL PORTUGUESE) produced this vivid rendition of our Uesama by charcoal.
Centuries later, the Oda were forced to move to the Tendo domain, and only by then the portrait popped up from the inheritance of the clan.
It was declared a family tresure and placed into the bodaiji, besides, a picture was conveniently taken and preserved during the Meiji era.
Obviously the original portrait was destroyed during a fire and only the picture was saved, picture that is now placed into the family temple of the Tendo Oda of Sanpoji (三宝寺) in Yamagata prefecture.

It sounds fishy, doesn't it?

I investigated over Giovanni Niccolò but besides his tiny biography over Wikipedia I couldn't find much. I quickly realized that despite being such a popular painter, the maestro of the first Art School in Nagasaki and someone who apparently brought in Asia the gusto for Western art, there are practically no paintings that could be credited to his hand.
The Japanese Wikipedia, that took this matter to heart, reveals that a famous screenfold portraying the "Western Kings on Horseback" (a very popular theme in Japan) can be recognized as his very work, but if that's true, we can see very little similarity with the realistic style of our portrait.
That Giovanni followed that archaic style of painting, connected to the artistic language of Portuguese origin, though, is a matter of fact.
Following the artworks that his Chinese and Japanese disciples left us as a trail along the Jesuit missions, we do see a similar maniera and language, that can allow us to believe that Giovanni's disciples came to imitate perfectly the style of their teacher.
As it's true that following a style doesn't mean that one can't "imitate nature" properly, it's very little probable that Giovanni, if he ever faced Nobukatsu, dared to produce such a realistic portrait, assuming that he was famous for his Jesuit style of art and that it would have been what Nobukatsu was expecting of him.

Here's a comparison of the portrait of Nobunaga, the portrait of one of the Kings credited to Giovanni Niccolò and one of the "Saviour of the World" paintings of Jesus (dating 1597) that were so popular in Japan back then and quite widespread as an icon:

Sure, comparing a drawing to a painting is kinda rough, but you can already spot the various differences of styles.
I couldn't find pencil or charcoal artworks dating the same period and area to make a proper comparison, otherwise that would have been interesting too.

Long story short, the suspicious over this portrait and the identity of the Oda oin there seem to have some serious foundation...

_{Credits: the main picture of this post comes from this blog. It's part of an exhibition in Azuchi.}