Rare style UNOKUBI 鵜首 TANTO, with Shirasaya, Edo period mumei

This is a slightly unusual Tanto.
The blade is short in overall length, but is very thick.
It appears to be a custom-made item.
It comes with a Shirasaya, which is perfect for storing the blade. (Only one blade is included.)

Signature : Mumei (Unsigned)
Nagasa : 184mm (7.24 in.) 
Sori : 6mm (0.24 in.) 
Total length : 335mm (13.19 in.) 
Motohaba : 23.9mm (0.94 in.) 
Sakihaba : 16.1mm (0.63 in.) 
Motokasane : 8.3mm (0.33 in.) 
Sakikasane : 5.7mm (0.22 in.) 
Blade Weight : 159g
Total Weight : 315g