Could a Mumei or Suriage Kotetsu become Juyo

[Utopianarian]

I know there are defining characteristics and rules with passing Juyo blades based on era of blade and if mei is intact. But in the case of a famous smith like Nagasone Kotetsu what would be the case if the sword itself showed undisputed evidence that the blade was forged by this smith.

[PNSSHOGUN]

There may need to be other factors with the sword, such as historical links/events directly associated with the sword, if it has detractions like Suriage. 

[Rivkin]

Juyo is a competition. Unsigned Kotetsu nearly always will lose to a signed one or a signed blade by any of the first class shinto smith and thus has almost no chance of becoming Juyo.

[Nihontocollector752]

Mumei and suriage edo sword has no chance

[Grey Doffin]

Except for the suriage Nanki Shigekuni katana that is Tokubetsu Juyo. Exceptions to every rule.

Grey

[Nihontocollector752]

@Grey Doffin interesting, any links to the zufu on that?

[Jussi Ekholm]

Here is the Nanki Shigekuni from Tokubetsu Jūyō 8.

 

 

Unfortunately I haven't got time now to check Jūyō Kotetsu swords right now, I can possbily do it some time next week. I don't have all of the books yet but I do have lot of them.

[Fuuten]

I was thinking along the lines of OP regarding the court auction Masayuki (Kiyomaru), of which the forum is probably well aware. Machi okuri did not stop that one from receiving Juyo papers(?).

[Nihontocollector752]

I don't think that has gone for juyo yet (the Masayuki) but given the rarity and renown of the smith it will probably pass even if slightly machiokuri

[Gakusee]

A couple of points. I did go through the Juyo Kotetsu and could not see any suriage swords. 
Secondly, slightly machiokuri is nowhere near the same “flaw” or “detractor” when positioning in the hierarchy for Juyo as is suriage. Sometimes machiokuri is not even detectable and people sometimes even say “possibly slightly machiokuri”. 
 

For old swords, where signed examples survive,  empirically I have noticed that broadly speaking the following hierarchy applies:  ubu zaimei > ubu kinzogan or suriage zaimei > suriage orikaeshi >  gakumei > suriage kiwame (I suppose with exception of Kochu, Kojo who are highly valued) > mumei. 
 

Of course the above is a crude generalisation and in fact there are Koto swords where you cannot realistically find zaimei swords (Soshu; few Kokuho exceptions) so you have to go with mumei or kiwame. Sometimes the kinzogan comes with such strong provenance (kinzogan were expensive to give so Daimyo blades by definition) or such strong quality that the blade is elevated through Juyo and TJ. 
 

For new swords, as is the case with Kotetsu, you really need zaimei ubu or at the very best undetectable little machiokuri but otherwise pristine nakago (and of course -sword). The Juyo criteria precisely state: “Blades made in the Muromachi period must be zaimei and blades from the Edo period and later, as a rule, must be ubu and zaimei to receive Juyo Token paper.”
 

So, the answer to your question is No.