Is this a real Koyama Munetsugu sword?

[riamken]

I may have the opportunity to purchase this sword. The markings appear to be correct for his "Koyama Munetsugu Sak" signature but I am cautious as I know he had fakers signing his name to things during his lifetime. Everything about the sword indicates that the time period is correct and all of the components that are there are right, just wary of the signature. Anyone have any experience with his work? Or even just more experience with the markings. I found some info online but that was limited.

Thank you in advance for any assistance you may provide. 

[PNSSHOGUN]

Hello ??? (you need to sign with your real name)

 

We will need better pictures of the blade, especially Hamon and Hada to give you any worthwhile advice.

[Brian]

I would bet 10 to 1 that this is gimei. Nothing there screams Munetsugu and one without papers would likely be a false signature.
But of course you have to check it out. Hamon, hada etc. There are FAR more fake signatures out there than real ones though.
 

[Jacques D.]

Not that difficult to see if it is gimei or not

 

http://www.e-sword.jp/sale/0810_2060syousai.htm

 

https://www.seiyudo.com/ka-040713.htm

 

http://www.tsuruginoya.com/mn1_3/a00042.html