Second mekugi ana at the end of nakago

[Marcin]

Why such slot was made?

It was for fitting longer blades into gunto koshirae? [Kabutogane/sarute]

Any typical koshirae? Late war type 3 with blades made with whatever can cut?

It indicates that blade is prewar? [Why waste material to forge longer nakago just to punch through it?]

 

[Ray Singer]

Shinobi-ana.

https://www.google.com/search?q="shinobi-ana"+site%3Amilitaria.co.za&rlz=1C1YTUH_enUS1164US1164&oq="shinobi-ana"+site%3Amilitaria.co.za&gs_lcrp=EgZjaHJvbWUyBggAEEUYOTIHCAEQIRiPAjIHCAIQIRiPAjIHCAMQIRiPAtIBCDI0NDhqMGo3qAIAsAIA&sourceid=chrome&ie=UTF-8

[Marcin]

Thank you! Great info. So even in old days some samurai would have this as possible back up.

[Kiipu]

The NMB thread linked to below will get you off to a good start.

Shinobi Ana 忍び孔

[lonely panet]

The type 3 was a late war sword. Quality control and economic conditions reduced time or skilled craftsmen so from my experiences the tsuka fit was always much poorer and required a 2nd mekugi to compensate for rushed products standards.

 

Even on gendai in type 3s this is considered appropriate 

[Marcin]

You can find funny things thinking about something. Fresh Tokuho mumei Echizen Rai. Ofcourse dunno how it looked before shortening [current nagasa is 71 cm]