Mizujushussho

The Mizujūshussho  (出所住水) is stated to be the unofficial weapon to be belonged to Shinwa Sozo who was stated to be the unofficial addition to the 7 Swordsmen of the Mist.

History
The concept of the sword was adapted and devised by Shinwa Sozo based on his clan's KKG and then introduced the idea to the greatest minds in the Bloody Mist.