Whos the swordsman with Kubikiribōchō?

[CrystalPad]

It's not zabuza. It can't be possible because Zabuza is close to Kakashi's age. Any clues as to who he is?

Oooops wrong section :T

 

[Red Slayer]

he is the guy who died against Dai

 

[Curse Mark]

he is the guy who died against Dai

Possibly. We don't know that for sure tho ya know