Square Mekugi-Ana...a thing?

[waljamada]

Ever seen a square mekugi ana?  Wondering if this was done for any specific reason?  Perhaps a thing done during a certain period...for....reasons?  Just a custom mekugi ana for a customer that wanted a square mekugi?

 

Either way, below is the example I came across:

[PNSSHOGUN]

It is more common to find on Tachi made in the Heian period, the significance of it on a later sword is somewhat mysterious.

[DoTanuki yokai]

https://markussesko.com/2013/09/14/the-secret-world-of-mekugi-ana/amp/
 

I think I read somewhere that in earlier times the pins of menuki where longer and was used as mekugi and the rectangular shape stopped them from rotating. 

Edit: Its actually in the article i have linked 

[ChrisW]

I've seen it on Kamakura and Muromachi era blades. Dan, if you're looking at this, care to share your tanto with the four mekugi-ana and in particular, the square one?

[O koumori]

Chris, it doesn't have a square mekugi ana, just multiple overlapping punched ones. 

(Musashi Chikashige, founder of Shitahara school)

[ChrisW]

My bad! I misremembered.

[waljamada]

Interesting, thank you for the education everyone.  It was my first time running into it and glad to hear the historical contexts of it.  Anyone with some unique mekugi-ana please post.  

 

That tanto's history has give it a pattern and design of its own.

[Jussi Ekholm]

Just noticed that Christian linked to an article by Markus above which had the info I was about to write on holes on Dans blade and so much more too.

 

The square hole is referred as masugata 枡形. Here is an example on my tachi from early Muromachi. I think the square hole is original hole for tachi mount and round hole later addon when it was mounted as katana.

[WillFalstaff]

While I have the book out.

 

 

[WillFalstaff]

[WillFalstaff]

[waljamada]

Here is the blade for the nakago at the top with description. 

 

Seems the square mekugi ana did make some appearances for a semi-wide period of time.